jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Apr 1995

Volume 77, Issue 8, pp. 3597-4159

Page 2 of 4 Pages Previous Page Next Page | Jump to Page

Low temperature properties of the filled skutterudite CeFe4Sb12

Donald T. Morelli and Gregory P. Meisner

J. Appl. Phys. 77, 3777 (1995); http://dx.doi.org/10.1063/1.358552 (5 pages) | Cited 175 times

Full Text: | Download PDF

Show Abstract
CeFe4Sb12 is a member of a class of advanced thermoelectric materials. In order to evaluate this material’s potential for such applications, we have measured a variety of its properties at low temperature, including thermal conductivity, thermoelectric power, electrical resistivity, Hall coefficient, and magnetic susceptibility. © 1995 American Institute of Physics.
Show PACS
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
72.15.Jf Thermoelectric and thermomagnetic effects
71.28.+d Narrow-band systems; intermediate-valence solids
75.50.Bb Fe and its alloys

Nickel silicide formation in silicon implanted nickel

Z. Rao, J. S. Williams, A. P. Pogany, D. K. Sood, and G. A. Collins

J. Appl. Phys. 77, 3782 (1995); http://dx.doi.org/10.1063/1.358553 (9 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
Nickel silicide formation during the annealing of very high dose (≥4.5×1017 ions/cm2) Si implanted Ni has been investigated, using ion beam analytical techniques, electron microscopy, and x‐ray diffraction analysis. An initial amorphous Si–Ni alloy, formed as a result of high dose ion implantation, first crystallized to Ni2Si upon annealing in the temperature region of 200–300 °C. This was followed by the formation of Ni5Si2 in the temperature region of 300–400 °C and then by Ni3Si at 400–600 °C. The Ni3Si layer was found to have an epitaxial relationship with the substrate Ni, which was determined as Ni3Si〈100〉∥Ni〈100〉 and Ni3Si〈110〉∥Ni〈110〉 for Ni(100) samples. The minimum channeling yield in the 2 MeV He Rutherford backscattering and channeling spectra of this epitaxial layer improved with higher annealing temperatures up to 600 °C, and reached a best value measured at about 8%. However, the epitaxial Ni3Si dissolved after long time annealing at 600 °C or annealing at higher temperatures to liberate soluble Si into the Ni substrate. The epitaxy is attributed to the excellent lattice match between the Ni3Si and the Ni. The annealing behavior follows the predictions of the Ni–Si phase diagram for this nickel‐rich binary system. © 1995 American Institute of Physics.
Show PACS
81.15.Np Solid phase epitaxy; growth from solid phases
61.72.up Other materials
81.30.Dz Phase diagrams of other materials

Crystallization and growth of Ni‐Si alloy thin films on inert and on silicon substrates

I. Grimberg and B. Z. Weiss

J. Appl. Phys. 77, 3791 (1995); http://dx.doi.org/10.1063/1.358554 (8 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The crystallization kinetics and thermal stability of NiSi2±0.2 alloy thin films coevaporated on two different substrates were studied. The substrates were: silicon single crystal [Si(100)] and thermally oxidized silicon single crystal. In situ resistance measurements, transmission electron microscopy, x‐ray diffraction, Auger electron spectroscopy, and Rutherford backscattering spectroscopy were used. The postdeposition microstructure consisted of a mixture of amorphous and crystalline phases. The amorphous phase, independent of the composition, crystallizes homogeneously to NiSi2 at temperatures lower than 200 °C. The activation energy, determined in the range of 1.4–2.54 eV, depends on the type of the substrate and on the composition of the alloyed films. The activation energy for the alloys deposited on the inert substrate was found to be lower than for the alloys deposited on silicon single crystal. The lowest activation energy was obtained for nonstoichiometric NiSi2.2, the highest for NiSi2—on both substrates. The crystallization mode depends on the structure of the as‐deposited films, especially the density of the existing crystalline nuclei. Substantial differences were observed in the thermal stability of the NiSi2 compound on both substrates. With the alloy films deposited on the Si substrate, only the NiSi2 phase was identified after annealing to temperatures up to 800 °C. In the films deposited on the inert substrate, NiSi and NiSi2 phases were identified when the Ni content in the alloy exceeded 33 at. %. The effects of composition and the type of substrate on the crystallization kinetics and thermal stability are discussed. © 1995 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.60.Dv Thermal stability; thermal effects
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder

A highly oriented Al[111] texture developed on ultrathin metal underlayers

Atsushi Kamijo and Tsutomu Mitsuzuka

J. Appl. Phys. 77, 3799 (1995); http://dx.doi.org/10.1063/1.358555 (6 pages) | Cited 12 times

Full Text: | Download PDF

Show Abstract
A highly oriented [111] texture is developed in ion beam sputtered Al films on metal underlayers of Ti, V, Cr, Co, Ni, Cu, or Y. The textured Al films show an extremely smooth surface. Deposition of highly textured Al films depends on the presence of this underlayer, the thickness of which must lie within a specific range that varies with the metal being used. We discuss here the mechanisms of texturing in terms of phenomenological surface‐interface energy balance considerations. The great tolerance for high‐power operations of Al films with a highly oriented [111] texture makes them particularly suitable for use as electrodes in surface acoustic wave devices. © 1995 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Orientation control of (Ca,Sr)CuO2 thin films

Satoshi Nagai, Hideaki Tanaka, Norifumi Fujimura, and Taichiro Ito

J. Appl. Phys. 77, 3805 (1995); http://dx.doi.org/10.1063/1.358556 (7 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Control of the orientation of (Ca,Sr)CuO2 films with (001) and (101) texture on glass substrates, and (110) and (101) texture on (001) MgO substrates was obtained by changing the sputtering conditions. Although (110) and (101) films on (001) MgO substrates were epitaxial, they showed a double positioning and fourfold rotation symmetry structure. Calculations using the cohesive energy between the film and the MgO single crystal substrate were used to confirm the epitaxial relationships between the film and the MgO substrate. The reason for the change in the texture of the films as a function of the substrate is also discussed. © 1995 American Institute of Physics.
Show PACS
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Cd Deposition by sputtering

Sputtering of boron‐doped graphite USB15—Investigation of the origin of low chemical erosion

R. Schwörer and J. Roth

J. Appl. Phys. 77, 3812 (1995); http://dx.doi.org/10.1063/1.359560 (6 pages) | Cited 11 times

Full Text: | Download PDF

Show Abstract
The changes in surface composition of USB15—a boron doped graphite containing 15 wt.% of boron—during bombardment with D ions were determined by in situ Auger electron spectroscopy at temperatures from 300 up to 1000 K. For energies above 100 eV no strong increase of the boron surface concentration could be observed even around 800 K, i.e., at the maximum for chemical erosion of pure graphite. Chemical factor analysis of the carbon Auger peak in this energy‐regime results in a much larger carbidic fraction of carbon atoms than suspected from the boron content of 15%. Thus, boron influences much more carbon atoms in their chemical reactivity with deuterium ions than is expected for the stoichiometric B4C precipitates. For ion energies below 100 eV a strong increase of boron surface concentration with decreasing ion energy at room temperature was observed. The chemical erosion of carbon in this energy regime is not suppressed by boron doping and indicates a different, surface related release process of hydrocarbon molecules. © 1995 American Institute of Physics.
Show PACS
68.35.Dv Composition, segregation; defects and impurities
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Interface structure of CdSe/ZnSe epilayers

Xue‐Hua Wu, Zhong‐Ling Peng, Shi‐Xing Yuan, and Fang‐Hua Li

J. Appl. Phys. 77, 3818 (1995); http://dx.doi.org/10.1063/1.358557 (5 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
Interface microstructure and strain relaxation of atomic‐layer‐epitaxy‐grown CdSe on ZnSe/GaAs〈001〉 was investigated by using transmission electron microscopy and high‐resolution transmission electron microscopy techniques. The CdSe epilayer is characterized with fluctuated misorientations along the interface, irregularly distributed stacking faults (SFs), and an array of misfit dislocations (MDs) composed of 60°, Lomer, and partial types. It is found that the fluctuated misorientation is related to the proportion of different 60° MDs and SFs, and this causes the local strain difference. The analysis of MDs is facilitated by using a digital image processing method and allows a clear image of a Lomer MD formed by interaction of two 60° MDs as well as the value of remaining local strains by measuring the density of MDs. © 1995 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.60.Bs Mechanical and acoustical properties
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Hydrogen ion interactions with silicon carbide and the nucleation of diamond thin films

J. M. Lannon, J. S. Gold, and C. D. Stinespring

J. Appl. Phys. 77, 3823 (1995); http://dx.doi.org/10.1063/1.358558 (8 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
Ultrahigh‐vacuum surface studies of hydrogen ion interactions with silicon carbide thin films were performed to provide new insights into the mechanisms of diamond thin‐film nucleation. These experiments were carried out at room temperature using hydrogen ions with energies of 10, 100, 500, and 2000 eV. In situ analyses using Auger electron spectroscopy indicated that silicon atoms were removed from the surface and near‐surface layers of the film, and the resulting carbon‐rich layers were converted to a mixture of sp2 and sp3 carbon. The relative amounts of sp2 and sp3 species formed were strongly dependent upon ion energy. The highest concentration of sp3 carbon was obtained using 500 eV ions. Theoretical considerations suggest this behavior was the result of both chemical and energy transfer effects. © 1995 American Institute of Physics.
Show PACS
81.15.Kk Vapor phase epitaxy; growth from vapor phase
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Microstructure of the Cr underlayer and its effect on Sm‐Co//Cr thin films

Y. Liu, B. W. Robertson, Z. S. Shan, S. H. Liou, and D. J. Sellmyer

J. Appl. Phys. 77, 3831 (1995); http://dx.doi.org/10.1063/1.358559 (5 pages) | Cited 14 times

Full Text: | Download PDF

Show Abstract
Sm‐Co film is a potential candidate for the future high density recording media of 10 Gb/in2 which requires bit sizes of the order of 300 nm and grain sizes of about 10 nm. This article investigates the microstructure of the Cr underlayer in Sm‐Co thin films and its effect on Sm‐Co thin films prepared by the dc magnetron sputtering technique. The grain size of the Cr underlayer is found to be about 25 nm. Grains with small angle misorientation usually form local agglomerates. Studies by transmission electron microscopy (TEM) bright field images at different defocus settings and by high resolution electron microscopy indicate that a large proportion of the grain boundaries have gaps. The gap width (about 1–3 nm) varies from place to place. The Sm‐Co films deposited on the Cr underlayer inherit similar gaps at positions adjacent to the grain boundary gaps of the Cr underlayer. Such gaps produce grain‐like contrast of about 25 nm in TEM bright field images. However, such contrast becomes weak as the thickness of the film increases and disappears at a thickness of 96 nm, suggesting the gaps are sealed at places far from the Cr underlayer. The effect of the Cr underlayer on magnetic properties are discussed. © 1995 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Structure of AlAs/GaAs distributed Bragg reflector grown on Si substrate by metalorganic chemical vapor deposition

T. Egawa, T. Jimbo, and M. Umeno

J. Appl. Phys. 77, 3836 (1995); http://dx.doi.org/10.1063/1.358560 (3 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
A vertical‐cavity surface‐emitting laser diode with 20 pairs of AlAs/GaAs distributed Bragg reflectors (DBRs) has been grown on a Si substrate using metalorganic chemical vapor deposition. Interfacial roughness and compositional profile of the AlAs/GaAs DBR structure were studied by cross‐sectional scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Auger electron spectroscopy. Cross‐sectional SEM and TEM observations reveal quasi‐periodic zigzag roughness and nonuniformity in the AlAs and GaAs layers. Auger electron spectroscopy reveals compositional transitions at the AlAs/GaAs heterointerfaces. A lower reflectivity of the AlAs/GaAs DBR on the Si substrate is caused by the degraded heterointerfaces. © 1995 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
42.55.Px Semiconductor lasers; laser diodes

Phase and composition depth distribution analyses of low energy, high flux N implanted stainless steel

Orhan Öztürk and D. L. Williamson

J. Appl. Phys. 77, 3839 (1995); http://dx.doi.org/10.1063/1.358561 (12 pages) | Cited 72 times

Full Text: | Download PDF

Show Abstract
The phase and composition depth distributions of a low‐energy (0.7 keV), high‐flux (2.5 mA/cm2) N implanted fcc AISI 304 stainless steel held at 400 °C have been investigated by step‐wise Ar+ beam sputter removal in conjunction with conversion electron Mössbauer spectroscopy and x‐ray diffraction (XRD). A metastable, fcc, high‐N phase (γN), with both magnetic and paramagnetic characteristics, was found to be distributed in the N implanted layer generated by the low‐energy, elevated temperature, implantation conditions. The magnetic γN was found to be ferromagnetic and was distributed in the highest N concentration region of the implanted layer (the top 0.5 μm) while the paramagnetic γN becomes predominant below 0.5 μm, where the N content is only slightly lower. The ferromagnetic state is linked to large lattice expansions due to high N contents (∼30 at.%) as determined by XRD and electron microprobe. The relatively uniform XRD N distribution to a depth of ∼1 μm suggests a sensitive dependence of the magnetic γN phase stability on N concentration and degree of lattice expansion. The XRD results also show that the N contents and depths depend on the polycrystalline grain orientation relative to the ion beam direction. The N was found to diffuse deeper in the (200) oriented polycrystalline grains compared to the (111) oriented grains and the N contents were significantly higher in the (200) planes relative to the (111) planes. The effect of compressive residual stresses (∼2 GPa) is considered. The scanning electron microscopy (SEM) analysis reveals quite clearly the uniform nature of the γN layers with a reasonably well defined interface between the γN layer and the substrate, suggesting uniform N contents with uniform layer thicknesses within a given grain. However, they also show significant variations in the γN layer thickness from one grain to the next along the N implanted layer, clearly supporting the XRD findings of the variation in N diffusivity with grain orientation. © 1995 American Institute of Physics.
Show PACS
61.72.S- Impurities in crystals
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
75.50.Bb Fe and its alloys

High resolution method for the analysis of admittance spectroscopy data

D. Maier, P. Hug, M. Fiederle, C. Eiche, D. Ebling, and J. Weese

J. Appl. Phys. 77, 3851 (1995); http://dx.doi.org/10.1063/1.358562 (7 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
There are several experimental methods which give information about the thermal relaxation times of the deep levels in a semiconductor. Analyzing the temperature dependence of the relaxation times, the activation energy and the cross section of the corresponding deep levels can be determined. An essential problem of such methods is the identification of the relaxation times in the measured signal. In the context of time‐dependent measurements such as photoinduced current transient spectroscopy and deep level transient spectroscopy, Tikhonov regularization was recently proposed as a high resolution method for this purpose. In this contribution it is proposed to apply Tikhonov regularization in order to identify the thermal relaxation times in admittance spectroscopy data. The method is tested and discussed using simulated data. Finally, admittance spectroscopy data of a GaAs diode are analyzed. The results demonstrate that the resolution of an ordinary admittance spectroscopy setup can considerably be improved by the application of Tikhonov regularization. © 1995 American Institute of Physics.
Show PACS
71.55.-i Impurity and defect levels
72.80.-r Conductivity of specific materials

Improvement of minority carrier diffusion length in Si by Al gettering

Subhash M. Joshi, Ulrich M. Gösele, and Teh Y. Tan

J. Appl. Phys. 77, 3858 (1995); http://dx.doi.org/10.1063/1.358563 (6 pages) | Cited 15 times

Full Text: | Download PDF

Show Abstract
Gettering is already an integral part of fabricating integrated circuits using Si substrates. It is anticipated that this will also be true for solar cell fabrication in the near future. A readily available technique compatible with solar cell processing is gettering by the Si wafer back surface Al. Recently, available solar cell efficiency studies have shown the beneficial effects of the wafer backside Al, including that of gettering, a wafer backside field, and grain boundary and dislocation passivation. In this article, we report on experimental results which showed that Czochralski Si wafer bulk minority carrier diffusion lengths can be substantially improved by wafer backside Al treatment, which also provided an effect of protection from environmental contamination. In these experiments, only the effect of gettering is present and therefore the results constitute an unambiguous demonstration of the benefits of gettering by Al. © 1995 American Institute of Physics.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.Yx Interaction between different crystal defects; gettering effect

Seminumerical simulation of dispersive transport in the oxide of metal‐oxide semiconductor devices

Seema Lathi and Amitava Das

J. Appl. Phys. 77, 3864 (1995); http://dx.doi.org/10.1063/1.358564 (4 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
Understanding and modeling of the device degradation mechanism in a metal‐oxide field‐effect transistor either due to hot carriers or ionizing radiation require simulation of hole /H+ ion transport in oxides. Because of its dispersive nature continuous‐time random‐walk‐based techniques are used for such simulations. A numerical technique to simulate dispersive transport of holes and H+ ions in amorphous SiO2 is described. Normalized flatband voltage shift and interface‐state density were computed as a function of time and compared with published experimental data. Simulation results show that numerical approach is accurate. Numerical simulation results also show that choice of trial functions for arbitrary value of dispersive parameter α is in general accurate; however, compared to trial function solutions, the numerical approach could be easily extended to two dimensions and integrated with conventional device simulators. © 1995 American Institute of Physics.
Show PACS
73.61.Ng Insulators
85.30.De Semiconductor-device characterization, design, and modeling

Electronic structures of Si1−xCx and Si1−x−yCxGey alloys

Jianjun Xie, Kaiming Zhang, and Xide Xie

J. Appl. Phys. 77, 3868 (1995); http://dx.doi.org/10.1063/1.359531 (4 pages) | Cited 19 times

Full Text: | Download PDF

Show Abstract
The linear‐muffin‐tin‐orbital method with the atomic‐sphere approximation is used to study the electronic structures of Si1−xCx and Si1−x−yCxGey alloys. The dependence of minimum band gap Eg, electronic density of states, and valence‐band width on alloy composition is investigated. All inequivalent atomic configurations for each given alloy composition are considered. It is found that the electronic structures of Si1−xCx and Si1−x−yCxGey show an unexpected variation of band gap versus the carbon concentration: For small to moderate concentrations of C in Si1−xCx and Si1−x−0.125CxGe0.125, the band gap decreases from that of pure Si. The lattice relaxation does not change such character of Eg. The peak positions in density of states shift downward as the carbon concentration in Si1−xCx and Si1−x−0.125CxGe0.125 increases; meanwhile, the valence band is monotonically widened. © 1995 American Institute of Physics.  
Show PACS
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
71.20.-b Electron density of states and band structure of crystalline solids

Changes in the trapping and recombination process of hydrogenated amorphous silicon in the Staebler–Wronski effect

P. Kounavis

J. Appl. Phys. 77, 3872 (1995); http://dx.doi.org/10.1063/1.358565 (7 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
The constant photocurrent method and the modulated photocurrent method (MPC) indicate that the defect density remains constant during the first minutes of the optical degradation of a‐Si:H or during its thermal annealing at temperatures lower than 150 °C. Under these conditions of exposure or annealing the optical bias dependence of the MPC (OBMPC) indicate that significant changes are induced to the trapping and the recombination process of the photocarriers. These changes are interpreted by a light induced increase of the capture probability of the deeper localized states of the energy gap for the photocarriers, increasing the recombination rate. The conclusions drawn are discussed with the predictions of various existing models concerning the Staebler–Wronski effect. Finally, a model is proposed which is combined with the bond breaking model and explains the present experimental results. © 1995 American Institute of Physics.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.61.Jc Amorphous semiconductors; glasses

Photoconductive spectroscopy of diamond grown by chemical vapor deposition

L. Allers and A. T. Collins

J. Appl. Phys. 77, 3879 (1995); http://dx.doi.org/10.1063/1.358566 (6 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
The photoconductivity of diamonds grown by chemical vapor deposition has been studied in the near infrared and visible spectral regions. The dominant photoconductive response has a threshold at approximately 1.5 eV. There is additional sharp structure in the region extending 165 meV to higher energy from the threshold, where 165 meV is the energy of the longitudinal optical (LO) phonon in diamond. It has also been found that there are minima in the photoconductivity spectrum at energies which are multiples of the energy of the LO phonon from the threshold energy. These minima have been associated with the decay of carriers to the bottom of the band by rapid emission of LO phonons. The optical absorption spectra of these diamonds show previously undocumented, sharp lines between 1.3 and 1.5 eV. These features are due to absorption to excited states of the same defect which is giving rise to the photoconductivity threshold at 1.5 eV. The sharp structure in the one‐phonon region of the photoconductivity spectrum has been associated with capture to these excited states by the emission of LO phonons. Similar structure in the same region of the absorption spectrum has been attributed to Fano resonances—interference effects caused by the interaction of bound states with a continuum of states © 1995 American Institute of Physics.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
78.40.Fy Semiconductors
78.30.-j Infrared and Raman spectra

Hydrogen passivation and its effects on carrier trapping by dislocations in InP/GaAs heterostructures

B. Chatterjee and S. A. Ringel

J. Appl. Phys. 77, 3885 (1995); http://dx.doi.org/10.1063/1.358567 (14 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
In previous work we reported on the stable passivation of dislocations in InP/GaAs heterostructures by plasma hydrogenation (Chatterjee et al., Appl. Phys. Lett. vol. 65, p. 58, 1994). In this article we investigate and compare the trapping kinetics and general trapping properties of dislocations in strain relaxed p‐InP grown on GaAs by metalorganic chemical vapor deposition prior to and after hydrogen passivation using deep level transient spectroscopy (DLTS) and current‐voltage‐temperature (I‐V/T) measurements to determine the complete role of hydrogen passivation in these heterostructures. Three hole traps, T1A, T1B, and T2, were detected and attributed to dislocations in heteroepitaxial p‐InP which displayed the logarithmic capture kinetics, extended dependence on fill pulse time, and broadened DLTS features expected for dislocation related traps. Quantitative analysis of the DLTS characteristics revealed progressive asymmetry in DLTS peak shape, an increase in characteristic peak width, and a decrease in activation energy as fill pulse time is increased until saturation values were reached.
These observations are explained on the basis of a distribution or band of energy states for each trap resulting from the interaction of electrically active sites either between closely spaced dislocations or along dislocation cores within the strain‐relaxed InP. For fill pulse times increasing from 1 μs to 10 ms, activation energies for T1A decreased monotonically from 0.80 to 0.65 eV, for T1B from 0.56 to 0.45 eV, and for T2 from 0.45 to 0.35 eV, with saturation occurring at the upper and lower limits for each trap, which indicates a qualitative measure of the energy spread for each trap. Plasma hydrogenation was not only found to passivate dislocations by reducing the trap concentration from ∼6×1014 to ∼3×1012 cm−3 for a 2 h exposure, but also strikingly altered their basic trapping properties. The qualitative measure of energy spread for the T1A and T2 traps were narrowed from ∼100 to 150 meV to ∼20 to 30 meV after a 2 h hydrogen exposure, whereas T1B was not detected after passivation. In addition, a simultaneous reduction in fill pulse saturation time, DLTS peak broadening, and peak shift as a function of hydrogen exposure time were observed. These observations suggest that hydrogen passivation modifies the dislocation trapping characteristics toward a more point defectlike behavior due to an increase in the average spacing between electrically active dislocation sites. This in turn reduces the interactions between these sites and narrows the distribution of states within each defect band. Further, reverse bias I‐V/T measurements revealed that the near midgap trap T1A, which was found to dominate the space charge generation current prior to passivation, is no longer dominant after hydrogen passivation. Instead a 2 h hydrogen treatment shifted the dominant center to an activation energy which more closely matches the shallow T2 level. © 1995 American Institute of Physics.
Show PACS
73.61.Ey III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
71.55.Eq III-V semiconductors

Native oxides on Si surfaces of deep‐submicron contact‐hole bottoms

Nahomi Aoto, Masaharu Nakamori, Shinya Yamasaki, Hiromitsu Hada, Nobuyuki Ikarashi, Koichi Ishida, Yuden Teraoka, and Iwao Nishiyama

J. Appl. Phys. 77, 3899 (1995); http://dx.doi.org/10.1063/1.358568 (9 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The effects of cleaning and treatment on the characteristics of contact‐hole‐bottom Si surfaces are investigated in order to reveal the origin of the increased contact resistance and to find treatment processes that can be used to obtain low contact resistance. Contact‐hole‐bottom Si surfaces were analyzed by using thermal desorption spectroscopy, transmission electron microscope, and energy‐dispersive x‐ray spectroscopy. Nonpatterned Si surfaces, which roughly simulate the properties of the contact‐hole‐bottom Si surfaces, were also analyzed by using x‐ray photoelectron spectroscopy. It is revealed that suboxide‐rich native oxide layers are formed on dry‐etch‐damaged Si surfaces. The oxide layer persists after the samples are cleaned with a mixture of NH4OH, H2O2, and H2O, and with a mixture of HCl, H2O2, and H2O, and even after dipping in diluted HF. The roughly 1.3‐nm‐thick oxide layer remains at the plugging‐poly‐Si/Si–substrate interface, increasing the contact resistance. The carbon contamination in the dry‐etch‐damaged layer contributes less to the increase in contact resistance. The dry‐etch‐damaged Si layer is removed by chemical dry etching. On the resultant damage‐free surfaces, native oxides with low suboxide density appear after NH4OH/H2O2/H2O and HCl/H2O2/H2O cleaning. Such oxides are easily removed by treatment with diluted HF, resulting in low contact resistance. An integrated contact‐hole treatment sequence is thus achieved to control the Si surface condition. The resultant low‐contact‐resistance deep‐submicron contact holes, plugged with P‐doped poly‐Si, can be applied for deep‐submicron contacts of 256 Mbit and larger dynamic random access memories. © 1995 American Institute of Physics.
Show PACS
73.40.Cg Contact resistance, contact potential
68.35.Dv Composition, segregation; defects and impurities
85.40.Ls Metallization, contacts, interconnects; device isolation

Electrical characteristics and thermal stability of ohmic contacts to p‐type In0.47Ga0.53/As/InP

Patrick W. Leech and Geoffrey K. Reeves

J. Appl. Phys. 77, 3908 (1995); http://dx.doi.org/10.1063/1.358569 (5 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
The electrical characteristics and thermal stability of Pd/Zn/Pd/Au, Pd/Au, Zn/Pd/Au, Au/Zn/Au, Ni/Zn/Ni/Au, and Pd/Mn/Sb/Pd/Au contacts to p‐type In0.47Ga0.53As/InP have been investigated. For all of the as‐deposited contacts, the specific contact resistance, ρc, was within the range between 1 and 3×10−5 Ω cm2. The thermal annealing of the contacts between 250 and 500 °C produced a differing effect on ρc for each of the metallization schemes. Based on ρc measurements, the thermal stability of the contacts at 400 °C showed an initial regime of low degradation rate with a subsequent transition to a higher rate regime. The exception to this trend was the Pd/Mn/Sb/Pd/Au contact for which no threshold was evident, and for which the dependence of degradation rate on time, t0.15, was lower than for the other configurations with t0.5. During aging at 500 °C, a single regime of high degradation rate was present. In both the low rate and high rate regimes, the type of interfacial metal was not a significant factor in determining the dependence of degradation rate on time. © 1995 American Institute of Physics.
Show PACS
73.40.Cg Contact resistance, contact potential

Impact ionization in GaAs metal–semiconductor field‐effect transistors with a lightly doped drain structure and an Al0.2Ga0.8As/GaAs heterobuffer layer

Junzi Haruyama and Humiaki Katano

J. Appl. Phys. 77, 3913 (1995); http://dx.doi.org/10.1063/1.358570 (6 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
Kink effects (abrupt increases in drain current) were observed with an abrupt increase of gate current (IG), substrate current (Isub), substrate potential (Vsub), and photoemission intensity (Iphoto) in GaAs metal–semiconductor field‐effect transistors (MESFETs) with a lightly doped drain (LDD) structure and an Al0.2Ga0.8As/GaAs heterobuffer layer. The kink drain voltage (VKD) increases as substrate temperature increases. Since impact ionization has a negative coefficient for increase of temperature, the increase of VKD indicates that impact ionization occurs at VKD. VKD also increases as VG becomes more negative and as the ratio of the dose of the silicon ions is reduced in the LDD region. Thus it is confirmed that impact ionization occurs at the drain side along the channel current path because those changes of VG and dose ratio reduce the electric field at the drain‐side channel. In addition, impact ionization coefficients were calculated from IG and Isub based on the method proposed by Hui et al. Both the coefficients were exponentially proportional to the negative inverse of the electric field, although the magnitude of Isub was approximately 250× greater than that of IG. On the other hand, it was found that Iphoto was linearly proportional to Vsub. It suggests that Iphoto depends on the number of holes which overflow the n‐GaAs channel/i‐GaAs buffer interface potential barrier into the channel layer. These behaviors of IG, Isub, Iphoto, and Vsub are attributed to this FET structure which has a thin channel layer with a high donor density and a heterobuffer layer. © 1995 American Institute of Physics.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
72.20.Ht High-field and nonlinear effects
85.30.Tv Field effect devices

Er‐related deep centers in GaAs doped with Er by ion implantation and molecular beam epitaxy

D. W. Elsaesser, Y. K. Yeo, R. L. Hengehold, K. R. Evans, and F. L. Pedrotti

J. Appl. Phys. 77, 3919 (1995); http://dx.doi.org/10.1063/1.358571 (8 pages) | Cited 11 times

Full Text: | Download PDF

Show Abstract
Deep level transient spectroscopy (DLTS) and temperature‐dependent Hall effect measurements were performed on undoped, n‐, and p‐type GaAs doped with Er either by ion implantation or during molecular beam epitaxial (MBE) crystal growth. For light Er doping (≲1017 cm−3), a hole trap was observed at 35 meV above the valence band, whereas for heavier doping (≳5×1017 cm−3), a hole trap was observed at 360 meV. Both traps were found in both ion implanted and MBE materials. The 35 meV center is attributed to the Er atom occupying the Ga site and acting as an isovalent impurity, whereas the 360 meV center is attributed to Er in an interstitial position. Furthermore, photoluminescence and DLTS measurements of Er‐implanted GaAs revealed that both the Er3+ intra‐4f‐shell emission intensity and concentration of the deep 360 meV centers were maximized at an annealing temperature of 750 °C, and they decreased at higher temperature anneals, while the concentration of the shallow 35 meV centers increased. © 1995 American Institute of Physics.
Show PACS
71.55.Eq III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors

Carrier transport properties of iodine‐doped (ZnS)3(ZnSe)42 ordered alloys grown by atomic layer epitaxy

Hiroyuki Fujiwara, Hideaki Kiryu, and Isamu Shimizu

J. Appl. Phys. 77, 3927 (1995); http://dx.doi.org/10.1063/1.358572 (7 pages) | Cited 11 times

Full Text: | Download PDF

Show Abstract
Iodine‐doped ordered alloys, given in a form of (ZnS)3(ZnSe)42, were grown on a GaAs(100) substrate by hydrogen radical‐enhanced chemical vapor deposition using atomic layer epitaxy. Iso‐buthyliodide was used for the first time as the doping source. A very high Hall mobility of 470 cm2/V s was obtained at room temperature in the slightly I‐doped sample (3×1016 cm−3). This high mobility is due to the elimination of structural fluctuations by forming a two‐dimensional ordered structure, which was confirmed by the satellite peaks in x‐ray diffraction spectra. Blue band‐edge emissions were found to be dominant at 35 K and room temperature in photoluminescence spectra. These results indicate that the formation of defects was minimized in these crystals by the layer‐by‐layer structure and the low‐temperature growth at 200 °C. © 1995 American Institute of Physics.
Show PACS
73.61.Ga II-VI semiconductors
73.50.Dn Low-field transport and mobility; piezoresistance

Raman spectroscopic analysis of the free carrier concentration in GaAs oval defects

P. S. Dobal, H. D. Bist, S. K. Mehta, and R. K. Jain

J. Appl. Phys. 77, 3934 (1995); http://dx.doi.org/10.1063/1.358573 (4 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The free carrier concentration at oval defects in silicon‐doped GaAs grown by molecular beam epitaxy has been studied on the basis of longitudinal‐optical (LO)‐phonon plasmon coupled mode frequency through Raman spectroscopy. The carrier concentration at the oval defects was found to be lower as compared to the defect‐free regions. The variations of surface depletion width with the concentration calculated from LO phonon intensities was also used to obtain the carrier concentration at the oval defects. Excellent agreement was found between the carrier concentrations obtained from these two methods. © 1995 American Institute of Physics.
Show PACS
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Photoconducting properties of a ladder polymer

K. S. Narayan, B. E. Taylor‐Hamilton, R. J. Spry, and J. B. Ferguson

J. Appl. Phys. 77, 3938 (1995); http://dx.doi.org/10.1063/1.358574 (4 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
The electronic properties of the ladder polymer BBL are investigated using steady state and transient photoconductivity techniques. The photocurrent response of the polymer film in the surface cell and sandwich cell configurations are compared along with the absorption spectra and the results correlated with the surface and bulk morphology. The steady state photocurrent shows a nonlinear response with respect to the electric field, and the photocurrent spectral response is accompanied by a significant tailing in the infrared region. The photocurrent is also studied as a function of photon intensity and chopper frequency. A long lived transient photocurrent (≳100 ms) is present on exposure to nanosecond laser pulses revealing the presence of deep traps. © 1995 American Institute of Physics.
Show PACS
73.61.Ph Polymers; organic compounds
73.50.Pz Photoconduction and photovoltaic effects
42.70.Jk Polymers and organics
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close