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1 Oct 1986

Volume 60, Issue 7, pp. R83-2643

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Some properties of Zn3P2 polycrystalline films prepared by hot‐wall deposition

S. Fuke, S. Kawarabayashi, K. Kuwahara, and T. Imai

J. Appl. Phys. 60, 2368 (1986); http://dx.doi.org/10.1063/1.337147 (4 pages) | Cited 8 times

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Zinc phosphide (Zn3P2) thin films have been deposited by hot‐wall deposition technique on glass substrate, and the deposition behaviors as well as structural properties of deposited films are studied. The source temperature and the temperature difference between source and substrate mainly affect the growth rate. Scanning electron microscope observation indicates the growth of columnar structure perpendicular to the substrate, and highly oriented thin films along the c axis are confirmed by x‐ray diffraction analyses. The resistivity of the films is strongly related to the phosphorus composition X in Zn(1−X)PX, and the films having higher X show lower resistivity. The direct absorption edge is obtained as about 1.5 eV from the optical absorption data.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
75.20.Ck Nonmetals

Damage of coherent multilayer structures by injection of dislocations or cracks

J. P. Hirth and A. G. Evans

J. Appl. Phys. 60, 2372 (1986); http://dx.doi.org/10.1063/1.337148 (5 pages) | Cited 35 times

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Experimental evidence indicates that coherent multilayer structures (strained superlattices) can be grown in a damage‐free state when the thickness of the layer is less than a critical value. The resistance of such structures to subsequent damage by dislocation or crack injection is examined in the present study. The structures are determined to exhibit damage resistance that decreases as either the layer thickness or the coherency strains increase.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Lm Deformation, plasticity, and creep

Minority‐carrier lifetime in doped and undoped n‐type CdxHg1−xTe

R. G. Pratt, J. Hewett, P. Capper, C. L. Jones, and N. Judd

J. Appl. Phys. 60, 2377 (1986); http://dx.doi.org/10.1063/1.337149 (9 pages) | Cited 23 times

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Measurements of minority‐carrier lifetime have been carried out on slices of n‐type CdxHg1−xTe (0.2<x<0.3) prepared by both normal Bridgman and accelerated crucible rotation (ACRT) Bridgman techniques. Some of these crystals were deliberately doped with a high level of a single impurity. A study of aging effects has been concluded. Lifetime variations with temperature are explained using a combination of band‐to‐band and Shockley–Read recombination processes. Frequently, a single level 10–30 meV below the conduction‐band edge was assumed, but for ACRT crystals it was necessary to postulate a second level. Attempts to identify the origin of the centers, by measurements on doped crystals, were only successful in the case of iron since it acts as a recombination center without providing conduction electrons in CdxHg1−xTe.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
81.40.Rs Electrical and magnetic properties related to treatment conditions

Observation of single‐carrier space‐charge‐limited flow in nitrogen‐doped α‐silicon carbide. III. Computer calculations

S. Tehrani, G. Bosman, L. L. Hench, and C. M. Van Vliet

J. Appl. Phys. 60, 2386 (1986); http://dx.doi.org/10.1063/1.337150 (10 pages) | Cited 1 time

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We report here computer calculations of current‐voltage characteristics, impedance, and noise in space‐charge‐limited (SCL) flow in SiC crystals composed of layered polytypes. The results are compared with previously reported experimental data [Part I of the same title, J. Appl. Phys. 58, 1562 (1985) and Part II of the same title, J. Appl. Phys. 58, 1571 (1985)], and are found to give excellent agreement. In contrast to the analytical computations reported previously, the diffusion term is not neglected. It is shown to play an important role at low and moderate bias voltage. Also, these computations show clearly that while many types of traps are present, ranging from 63 to 367 meV below the conduction band, at a given temperature only one trap determines the I‐V characteristics. On the contrary, in the impedance and in the generation‐recombination noise spectra, many traps show up simultaneously and must be taken into account. In general, the main features of the analytical theory developed by Van Vliet et al. are confirmed.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.70.+m Noise processes and phenomena
72.20.Ht High-field and nonlinear effects
72.80.Jc Other crystalline inorganic semiconductors

Molecular material‐based junctions: Formation of a Schottky contact with metallophthalocyanine thin films doped by the cosublimation method

M. Maitrot, G. Guillaud, B. Boudjema, J. J. André, and J. Simon

J. Appl. Phys. 60, 2396 (1986); http://dx.doi.org/10.1063/1.337151 (5 pages) | Cited 32 times

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A new method for obtaining thin films of doped molecular materials in a complete absence of oxygen is described. It consists in simultaneously subliming under vacuum the electroactive compound—a metallophthalocyanine—and the electron acceptor or electron donor doping agent. The extent of doping is controlled by the relative rates of sublimation. The ac and dc electrical properties of thin films are determined under high vacuum as to eliminate the influence of oxygen which has been previously shown to be of the utmost importance. Both p‐ and n‐type dopings have been achieved; the increase of conductivity reaches six orders of magnitude for p‐type doping with dichlorodicyanoquinone (DDQ). For the first time a rectifying contact between doped phthalocyanine thin films and aluminum has been observed in strict absence of oxygen.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ng Insulators
73.40.Ns Metal-nonmetal contacts

Electron‐beam‐induced current near the localized defects in a polycrystalline semiconductor

A. Romanowski

J. Appl. Phys. 60, 2401 (1986); http://dx.doi.org/10.1063/1.337152 (5 pages)

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The short‐circuit current in a polycrystalline semiconductor may be distorted by the local defects or by the local interface defects (variation of the effective recombination velocity at the grain boundary). These defects can be determined from the steady‐state electron‐beam‐induced current. The expression for the contrast coefficient C for the above defects are given. In the analysis, the generation of the excess carriers is assumed to be uniform in a sphere tangent to the semiconductor surface. The p‐n junction is placed on the surface of the semiconductor.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.-y Defects and impurities in crystals; microstructure
79.20.Kz Other electron-impact emission phenomena

Semiconductor analysis using organic‐on‐inorganic contact barriers. II. Application to InP‐based compound semiconductors

S. R. Forrest, M. L. Kaplan, and P. H. Schmidt

J. Appl. Phys. 60, 2406 (1986); http://dx.doi.org/10.1063/1.337153 (13 pages) | Cited 27 times

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Organic‐on‐inorganic (OI) contact barrier devices have been applied to the study of InP and In0.53Ga0.47As surfaces. The characteristics of these devices differ from OI diodes fabricated using Si or Ge substrates in that the contact barriers for InP‐based devices are relatively small (≤0.55 eV), and the diode characteristics are governed by a high density of states at the organic/inorganic interface. We present current‐voltage and frequency‐dependent admittance‐voltage characteristics for OI diodes employing 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) and related compounds as the organic thin‐film material. Analysis of characteristics using a theory presented previously [S. R. Forrest and P. H. Schmidt, J. Appl. Phys. 59, 513 (1986)] indicates that the surface state density is (i) independent of the organic material employed, and (ii) sensitive to the exposure of the surface to chemical treatment prior to the organic thin‐film deposition. Using techniques derived previously, we determine the magnitude and energy distribution of the density of states at InP and In0.53Ga0.47As surfaces. It is found that the densities of states can vary between mid‐1011 and 1015 cm−2 eV−1, depending on the surface treatment employed. Furthermore, some surface treatments result in an organic/In0.53Ga0.47As barrier height that is strongly dependent on applied voltage due to the presence of a high density of interface states.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.20.-r Electron states at surfaces and interfaces
71.20.-b Electron density of states and band structure of crystalline solids
81.65.-b Surface treatments

Experimental study of nonlinear current‐voltage behavior in undoped polycrystalline silicon

Dae M. Kim, Feng Qian, S. S. Ahmed, H. K. Park, and J. L. Sachitano

J. Appl. Phys. 60, 2419 (1986); http://dx.doi.org/10.1063/1.337154 (3 pages) | Cited 3 times

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Electrical conduction data from undoped low‐pressure chemically vapor deposited polycrystalline silicon thin films at room temperature and above are presented. The physical mechanisms pertinent to general current‐voltage characteristics are experimentally interrogated from three different viewpoints. In the nonlinear current‐voltage region, the sheet resistance Rs is shown to vary drastically depending on the device aspect ratio for given applied electrical field math. The nonscalability of Rs with respect to math, the temperature behavior of Rs, and the photoconductivity data indicate that the nonlinear current‐voltage behavior cannot be attributed to field‐enhanced conductivity. Other possible mechanisms responsible for observed nonlinearity are discussed.
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73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
73.25.+i Surface conductivity and carrier phenomena
72.40.+w Photoconduction and photovoltaic effects

Optimization of BF2+ implanted and rapidly annealed junctions in silicon

I‐W. Wu, R. T. Fulks, and J. C. Mikkelsen

J. Appl. Phys. 60, 2422 (1986); http://dx.doi.org/10.1063/1.337155 (17 pages) | Cited 30 times

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The electrical properties and defect characteristics of shallow junctions fabricated by using BF2+‐ion implantation and followed by either furnace or rapid thermal annealing (RTA) have been investigated. The RTA temperature‐time cycle was optimized in terms of leakage current, junction depth, and sheet resistivity of junctions. Specifically, shallow p+ junctions (∼180 nm) with low leakage current (∼2 nA/cm2 at −5 V) were obtained with 49‐keV, 2×1015‐cm−2 BF2+ implantation and RTA at 1050 °C for 15 s. The effects of a Si+ preamorphizing implant and pre‐ or post‐RTA low‐temperature furnace anneal were also studied. p+/n diodes fabricated with a preamorphizing implantation exhibit about 3 orders of magnitude higher leakage current than the diodes without preimplantation. The excessive leakage current of the preamorphized junctions arises from a band of post‐annealing defects located in the depletion region of the n well (from ∼220 to 420 nm). Samples without the Si+ implant have very shallow and narrow defect bands (from ∼70 to 120 nm) located inside the heavily doped p+ region. The depth distribution of post‐annealing defects corresponds to the partially amorphized (heavily damaged) regions near the as‐implanted crystalline/amorphous interfaces. Furthermore, a low‐temperature furnace anneal (550 °C for 1 h) before or after RTA treatment reduces leakage current for diodes without preimplantation. This reduction of leakage current by the two‐step annealing coincides with the relaxation of the implant‐induced stress in the junction, as measured by substrate curvature. The post‐RTA anneal is found to be more effective than the pre‐RTA anneal, both in terms of leakage current and the amount of stress relief. Channeling tails were observed in secondary‐ion mass spectrometry boron profiles of BF2+‐implanted samples, and Si+ preamorphization eliminates them. However, identical carrier concentration profiles are obtained by spreading carrier‐resistance measurements for samples with or without preamorphization, which suggests that the channeled boron atoms remain in the interstitial sites after RTA and hence are inactive.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.Bb Theories and models of crystal defects
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

The effects of vacuum conditions on epitaxial Al/GaAs contacts formed by molecular‐beam epitaxy

M. Missous, E. H. Rhoderick, and K. E. Singer

J. Appl. Phys. 60, 2439 (1986); http://dx.doi.org/10.1063/1.337156 (6 pages) | Cited 26 times

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The effects of the quality of the vacuum on the epitaxy of aluminum on (100) gallium arsenide have been investigated. It was found that leaving the ion gauge running during the cooling down of the GaAs prior to the deposition of the Al and the presence of a helium cryopump both affected the nature of the epitaxy and the height of the resulting Schottky barrier. Reproducible results were only obtained with the ion gauge off and the cryopump on. The Al film was found to take up the (100) orientation irrespective of the reconstruction of the GaAs surface [c(2×8), c(4×4), or (4×6)]. The height of the Schottky barrier on n‐type GaAs was 0.77±0.01 eV, and was independent of the GaAs reconstruction. The I‐V characteristics were the most nearly ideal that have been reported, a plot of log{I/[1−exp(−qV/kT)]} vs V being linear over the whole voltage range from +0.5 to −1.0 V, with an ideality factor of 1.01 which can be explained solely in terms of image‐force lowering. The barrier height on p‐type GaAs was 0.64±0.01 eV, also irrespective of the GaAs reconstruction, so that ϕbn+ϕbp is equal to the band gap within the experimental error.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts

Morphology and kinetics of crystallization of amorphous V75Si25 thin‐alloy films

F. Nava, B. Z. Weiss, K. N. Tu, D. A. Smith, and P. A. Psaras

J. Appl. Phys. 60, 2445 (1986); http://dx.doi.org/10.1063/1.337157 (8 pages) | Cited 13 times

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Electrical and microstructural changes of coevaporated V75Si25 alloy thin films have been studied as a function of temperature from room temperature to 830 °C. In situ resistivity measurements, hot‐stage transmission electron microscopy, Rutherford backscattering spectroscopy and the Seeman–Bohlin glancing angle incidence x‐ray diffraction technique were applied. Upon heat treatment at a heating rate of 8 °C/min, a sharp decrease in resistivity occurs at ∼670 °C which results from an amorphous to crystalline phase transformation. The crystallized phase was identified as V3Si. The mechanism of transformation is random nucleation at a rapidly decreasing rate and a fast quasi‐isotropic growth. The kinetics of crystallization have been studied by utilizing electrical resistivity measurements during isothermal heat treatment. Six different temperatures between 570 °C and 630 °C were adopted. The apparent activation energy (∼3.6 eV) obtained from isothermal measurements was found to be in agreement with that obtained from nonisothermal treatments at varying rates of heating. The distinct change of the Avrami mode parameter from 4 to 2 at a constant value of t/τ during the process of crystallization is not immediately understood.
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81.40.Rs Electrical and magnetic properties related to treatment conditions
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
73.61.At Metal and metallic alloys
68.55.-a Thin film structure and morphology

First observation of two‐dimensional hole gas in a Ga0.47In0.53As/InP heterojunction grown by metalorganic vapor deposition

M. Razeghi, P. Maurel, A. Tardella, L. Dmowski, D. Gauthier, and J. C. Portal

J. Appl. Phys. 60, 2453 (1986); http://dx.doi.org/10.1063/1.337158 (4 pages) | Cited 6 times

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We report the observation of a two‐dimensional (2D) hole gas in Ga0.47In0.53As/InP heterojunction grown by metalorganic chemical‐vapor deposition. In a sample with a total hole density ptot =7.6×1011 cm−2 a Hall mobility μH =10 500 cm2/V s was reached at 4.2 K. Angle‐dependent Shubnikov–de Haas measurements as well as quantized Hall effect observations confirmed the two‐dimensionality of the system. In contrast to the case of the 2D hole gas in GaAs/AlGaAs, low‐temperature persistent photoconductivity was observed, significantly increasing the hole density at the interface.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Interface excitations in layered structures with metallized surfaces

Manvir S. Kushwaha

J. Appl. Phys. 60, 2457 (1986); http://dx.doi.org/10.1063/1.337159 (5 pages) | Cited 7 times

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A theoretical investigation has been made of the interface excitations associated with the double inversion layers of semiconductor‐insulator‐semiconductor structure with metallized surfaces. The general dispersion relation has been derived using the local electromagnetic theory. The numerical computation is performed in the nonretardation limit (c→∞) for the structure assumed to be made up of n‐type silicon‐silicon‐dioxide‐p‐type silicon. Theoretical results for finite oxide thickness with respect to separation of the metallic surfaces are shown. These excitations can be regarded as the uncoupled (for infinite oxide thickness) and coupled modes (for finite oxide thickness) whose components are the two‐dimensional‐electron‐gas plasmon and the two‐dimensional‐hole‐gas plasmon. The finiteness of the structure presents some interesting variations in the frequencies of the plasma modes.
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73.40.Ty Semiconductor-insulator-semiconductor structures
73.61.Ng Insulators

Subthreshold response of rf SQUIDs to a general external perturbation

Adi R. Bulsara

J. Appl. Phys. 60, 2462 (1986); http://dx.doi.org/10.1063/1.337160 (15 pages) | Cited 7 times

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We consider a rf SQUID subjected to an external magnetic flux that includes dc, periodic, and stochastic components. Using a previously developed linearization technique, the response of the SQUID (below its hysteresis threshold) to this force is determined as a function of the internal parameters of the device. The measurement process, wherein the flux sensed by the SQUID is coupled to a tank circuit, is also considered. The results obtained, using the linearization technique referred to above, are compared with previously reported work on this subject. It is seen that, while not exact, this technique allows one to compute, analytically, the response (measured as an autocorrelation function or its associated spectral density) very accurately below the SQUID hysteresis threshold.
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85.25.-j Superconducting devices
74.90.+n Other topics in superconductivity (restricted to new topics in section 74)

Comparison of calculated and measured hysteresis loss in multifilamentary superconducting wire

M. Ashkin and G. R. Wagner

J. Appl. Phys. 60, 2477 (1986); http://dx.doi.org/10.1063/1.337161 (5 pages) | Cited 1 time

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A previously developed theory for a single round filament of type II superconductor is applied to hysteresis losses in multifilamentary composite conductors. The single filament theory was extended for a wider range of time varying field amplitudes. Two contrasting wires were used to test the theory which predicts a universal curve for the loss in all conductors. A very close agreement was obtained in all details between theory and experiment for the wire with widely spaced (∼2.5 μm) large‐diameter (15 μm) filaments. The other wire had closely spaced (<1 μm) small‐diameter (2 μm) filaments and the shapes of the loss versus field plots for theory and experiment were in excellent agreement for this case. However, the effective filament diameter and superconductor volume fraction λ extracted from fitting the theory and measurements are much larger than the physical diameter and slightly larger than the physical λ, respectively. This is expected due to the proximity effect and possible interfilament contact. This effective diameter is approximately the size of clearly defined filament bundles.
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74.25.N- Response to electromagnetic fields
74.25.-q Properties of superconductors
85.25.-j Superconducting devices

Thermal stability and aging effect of hydrogen‐implanted bubble garnet films

R. Imura and Y. Sugita

J. Appl. Phys. 60, 2482 (1986); http://dx.doi.org/10.1063/1.337162 (6 pages) | Cited 3 times

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Aging and thermal stability have been studied for a hydrogen‐implanted bubble garnet by measuring the effective anisotropy field change Δ(Hk−4πMs) and the lattice strain (Δa⊥/a) in the normal direction to the film. After annealing, a large decrease of Δ(Hk−4πMs) has been observed due to the out‐diffusion of hydrogen. It has been found that a larger Δ(Hk−4πMs) is kept after annealing in samples with SiO2 deposited on the garnet surface. The relaxation process of (Δa⊥/a) corresponding to Δ(Hk−4πMs) shows two activation energies EA (0.8 eV and 1.6 eV) for H+2 ‐implanted samples. A fast relaxation process (EA =0.8 eV) is peculiar to the H+2 ‐implanted samples due to the out‐diffusion of hydrogen and has not been observed for He+ or Ne+ implanted samples. From the aging test, it has been established that the lifetime t is about 5000 years to assure 99% stability of Δ(Hk−4πMs) at 100 °C for samples stabilized at 400 °C after SiO2 deposition.
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68.60.Dv Thermal stability; thermal effects
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.30.Gw Magnetic anisotropy

Growth‐induced anisotropy in bismuth: Rare‐earth iron garnets

V. J. Fratello, S. E. G. Slusky, C. D. Brandle, and M. P. Norelli

J. Appl. Phys. 60, 2488 (1986); http://dx.doi.org/10.1063/1.337163 (10 pages) | Cited 16 times

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The bismuth‐doped rare‐earth iron garnets, (R3−x−yBixPby)Fe5O12 (Bi:RIG, R=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), were prepared under constant growth conditions to investigate the influence of ionic species on the bismuth‐based growth‐induced uniaxial anisotropy Kgu. The effect of ionic species on growth‐induced anisotropy in Bi:RIG was not consistent with the ionic size model of site ordering. In particular, Bi:SmIG, Bi:EuIG, and Bi:TbIG displayed high growth‐induced anisotropies, up to 331 000 erg/cm3 at room temperature for x≊0.5. The temperature dependence of these Kgu’s was somewhat higher than that of the well studied Bi:YIG. The site ordering of Bi can be modeled by assuming that small, low‐oxygen‐coordination BiO+3−2ww melt complexes have a strong site selectivity for small, high‐oxygen coordination sites at the growth interface.
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75.30.Gw Magnetic anisotropy
75.70.Kw Domain structure (including magnetic bubbles and vortices)
81.10.Dn Growth from solutions
85.70.Ge Ferrite and garnet devices

Mössbauer effect of dilute Fe in sputtered Co‐Cr films

F. T. Parker

J. Appl. Phys. 60, 2498 (1986); http://dx.doi.org/10.1063/1.337164 (4 pages) | Cited 3 times

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Mössbauer effect measurements have been obtained on sputtered Co–Cr films containing a small amount of iron, with compositions Co76Cr20Fe4. Two features are observed: a single line (about 25% of the spectral area) and a broadened, magnetically split spectrum. From the isomer shift and lack of magnetic splitting in the former, the nonmagnetic phase in sputtered Co–Cr alloys is identified as being nearly pure Cr. In particular, the nonmagnetic phase can contain less than a few percent of the initial Co concentration. The magnetic phase has a decreased average magnetic hyperfine field relative to Fe in Co, and an isomer shift consistent with a Cr concentration about one‐half that of the initial Cr concentration. A substantial perpendicular polarization of the Fe moments is seen, although magnetic data indicate an easy plane orientation. The phase segregation in Co–Cr films is shown to be similar to the ‘‘475 °C embrittlement’’ long known in Fe–Cr alloys, and to the segregation that occurs in ductile Fe–Co–Cr–Si permanent magnets.
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75.70.-i Magnetic properties of thin films, surfaces, and interfaces
76.80.+y Mössbauer effect; other γ-ray spectroscopy
64.75.-g Phase equilibria
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Selective self‐optical compensation effect for a newly discovered acceptor‐associated emission in Zn+ ion‐implanted GaAs

Nobukazu Ohnishi, Yunosuke Makita, Katsuhiro Irie, Kazuhiro Kudo, Toshio Nomura, Hideki Tanaka, Masahiko Mori, and Yoshinobu Mitsuhashi

J. Appl. Phys. 60, 2502 (1986); http://dx.doi.org/10.1063/1.337165 (3 pages) | Cited 12 times

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Photoluminescence measurements were carried out at 2 K for Zn+ ion‐implanted GaAs, where the concentration of Zn was widely varied from 3×1016 to 1×1021 cm−3. Two Zn+‐associated emissions were formed. One emission is at 1.512 eV, g, and the other emission [g‐g] is just below g and this moves towards the lower energy level with increasing Zn concentration, [Zn]. The intensity of [g‐g] was enhanced with increasing [Zn], up to [Zn]=3×1017 cm−3, and was gradually suppressed for [Zn] beyond that concentration. This selective self‐optical compensation effect (SSOC) for [g‐g] was found to occur for moderately heavy ion acceptor species such as Zn and Cd, although [g‐g] is a common emission among many other acceptor impurities. In addition two new emissions were observed between g and [g‐g] at certain [Zn]. Preliminary theoretical explanations are presented for this SSOC effect.
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78.40.Fy Semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Characterization of optically active sites in CaF2:Ce,Mn from optical spectra

S. W. S. McKeever, M. D. Brown, R. J. Abbundi, H. Chan, and V. K. Mathur

J. Appl. Phys. 60, 2505 (1986); http://dx.doi.org/10.1063/1.337112 (6 pages) | Cited 20 times

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In this work we study CaF2:Ce,Mn and use optical absorption, photoluminescence (excitation and emission), and x‐ray‐induced luminescence to characterize the role played by Ce in various lattice sites during these processes. The data indicate that energy transfer takes place from Ce to Mn, predominantly from Ce3+ in tetragonal sites (i.e., Ce3+‐F−int centers with C4v symmetry). There is also some evidence of transfer from higher‐order clusters of these defects. In contrast, however, we note that there is no evidence of energy transfer in x‐ray‐excited luminescence; an increase in the Ce concentration causes a decrease in the Mn2+ emission. It appears from the present investigations that, during x‐ray excitation, nonlocally compensated Ce3+ ions of cubic symmetry compete with Mn2+ ions for free electrons released during irradiation. Thus, the data indicate that tetragonal Ce3+ sites are dominant during UV excitation and give rise to energy transfer to Mn2+, whereas cubic Ce3+ sites are dominant during irradiation with high‐energy ionizing radiations and no energy transfer takes place.
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78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics
78.55.Hx Other solid inorganic materials
78.70.En X-ray emission spectra and fluorescence

Lifetimes, ionization energies, and discussion of the emission lines in the 1.5040–1.5110‐eV range in GaAs

D. C. Reynolds, K. K. Bajaj, C. W. Litton, G. Peters, P. W. Yu, R. Fischer, D. Huang, and H. Morkoç

J. Appl. Phys. 60, 2511 (1986); http://dx.doi.org/10.1063/1.337113 (6 pages) | Cited 9 times

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We have calculated the recombination lifetimes for donor‐acceptor (D‐A) pairs having separations of 50–70 Å and find very good agreement with measured lifetimes. We have also measured the ionization energies of the transitions in the same spectral region using the temperature dependence of line intensity. The estimated ionization energies of D‐A pairs in this spectral region agree very well with the measured ionization energies. A model has been presented for the g lines, which accounts for the origin of the g lines in both GaAs and InP.
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78.40.Fy Semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Acoustic properties of proton‐exchanged LiNbO3 studied using the acoustic microscopy V(z) technique

P. J. Burnett, G. A. D. Briggs, S. M. Al‐Shukri, J. F. Duffy, and R. M. De La Rue

J. Appl. Phys. 60, 2517 (1986); http://dx.doi.org/10.1063/1.337114 (6 pages) | Cited 13 times

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We report measurements of proton‐exchanged LiNbO3 using acoustic microscopy in the V(z) mode, together with optical waveguide mode observations. In the present case, samples were prepared using dilute benzoic acid containing a small mole percent of lithium benzoate. Substantial changes in surface acoustic wave (SAW) propagation velocity due to proton exchange have been observed on all three major‐axis crystal cuts, with both increase and decrease in velocity occurring, depending on propagation direction. Changes in attenuation are also observed. Using the V(z) technique with a line‐focus cylindrical lens has enabled complete velocity surfaces for proton‐exchanged lithium niobate to be obtained with reasonable precision, based on simplified isotropic calculations of acoustic propagation in layered media and the assumption that the proton‐exchange region is uniform with a depth obtainable from optical waveguide mode calculations. It is concluded that the V(z) acoustic microscopy technique can provide a powerful tool in the study of the SAW properties of proton‐exchanged LiNbO3.
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78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.35.Pt Surface waves in solids and liquids
42.79.Gn Optical waveguides and couplers

Optical properties of UV laser photolytic deposition of hydrogenated amorphous silicon (a‐Si:H)

H. Zarnani, H. Demiryont, and G. J. Collins

J. Appl. Phys. 60, 2523 (1986); http://dx.doi.org/10.1063/1.337115 (7 pages) | Cited 9 times

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The effects of substrate temperature on the optical properties of the laser assisted chemical vapor deposited (L‐CVD) thin films of amorphous‐silicon–hydrogen alloy (a‐Si:H) are investigated herein. A controlled substrate temperature Ts from 35 to 350 °C was used to vary the hydrogen content in the films. The spectrophotometric transmittance characteristics of the L‐CVD a‐Si:H films are used to evaluate the optical parameters, including: refractive index n(E); extinction coefficient k(E); and the thickness d of the samples. The L‐CVD a‐Si films are obtained for Ts >340 °C. The refractive index and energy gap Eg of the L‐CVD a‐Si films are found to be 3.4 and 1.55 eV, respectively. The optical absorption spectra α vs E of the L‐CVD a‐Si:H films exhibit Tauc, Urbach, and Urbach tail (shoulder) regions. The ratio of photoconductivity/dark conductivity (σP/σD) of L‐CVD a‐Si:H films having coplanar electrode geometry with Ag electrodes are experimentally determined. The σP/σD ratio, one rough measure of electronic quality, exhibits a maximum for the L‐CVD a‐Si:H films deposited at Ts =280 °C with σP/σD =5×105,σD =2.5×10−11 (Ω cm)−1, and the minimum defect density is 3.1×1016 cm−3.
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75.20.Ck Nonmetals
81.40.Tv Optical and dielectric properties related to treatment conditions
73.61.Cw Elemental semiconductors
73.61.Ey III-V semiconductors
73.61.Ga II-VI semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Photoelectron spectra of amorphous SixHy alloy films: The effect of microstructure on the Si‐2p level shift

S. R. Das, J. B. Webb, S. C. de Castro, and V. S. Sundaram

J. Appl. Phys. 60, 2530 (1986); http://dx.doi.org/10.1063/1.337116 (6 pages) | Cited 3 times

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Depending on the deposition conditions, amorphous SixHy alloy films prepared by planar rf reactive magnetron sputtering exhibit one of three types of microstructure: (i) type A with no discernible microstructural features down to the 20‐Å level and with a smooth uniform density; (ii) type B consisting of high‐density regions of 50–200‐Å lateral dimensions separated by a low‐density network; and (iii) a two‐level (type C) microstructure consisting of 300–500‐Å dimensions columns separated by a pronounced low‐density network. The columns, in turn, are composed of 50–200‐Å dimension high‐density regions interspersed with low‐density network. The Si‐2p level in these alloy films, determined by x‐ray photoelectron spectroscopy, is observed to be strongly influenced by the microstructure of the film. A shift in the Si‐2p level, systematically varying with the hydrogen concentration, is observed in alloy films with type B and type C microstructures. No shift is observed, irrespective of the hydrogen concentration, in alloy films with type A microstructure. The photoelectron spectra are examined in the light of the vibrational spectra of the films as measured by Fourier transform infrared techniques. The dependence of the Si‐2p level shift on the microstructure and the variation with hydrogen concentration are explained qualitatively in terms of the differences in the silicon–hydrogen bonding in amorphous SixHy films with dissimilar microstructures.
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68.55.-a Thin film structure and morphology
81.65.-b Surface treatments
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Plasma‐enhanced growth and composition of silicon oxynitride films

C. M. M. Denisse, K. Z. Troost, J. B. Oude Elferink, F. H. P. M. Habraken, W. F. van der Weg, and M. Hendriks

J. Appl. Phys. 60, 2536 (1986); http://dx.doi.org/10.1063/1.337117 (7 pages) | Cited 47 times

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Silicon oxynitride films with varying oxygen/nitrogen ratio were grown from SiH4, N2O, and NH3 by means of a plasma‐enchanced chemical vapor deposition process. The elemental composition of the deposited films was measured by a variety of high‐energy ion beam techniques. To determine the chemical structure we used Fourier transform infrared absorption spectroscopy and electron‐spin resonance. Ellipsometric data and values for mechanical stress are also reported. We show that the entire range of compositions from silicon oxide to silicon nitride can be covered by applying two different processes and by adjusting the N2O/NH3 gas flow ratio of the respective processes. It is suggested that the N2O/SiH4 gas flow ratio is the major deposition characterization parameter, which also controls the chemical structure as far as the hydrogen bonding configuration is concerned. We found that the films contain significant amounts of excess silicon and that the mechanical stress in the oxynitrides is lower than in plasma nitride. The electron‐spin density is low (∼1017/cm3) in all samples.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.Nq Composition and phase identification
68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
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