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1 Feb 2007

Volume 101, Issue 3, Articles (03xxxx)

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Surface treatment effect on temperature-dependent properties of InGaP/GaAs heterobipolar transistors

Tzu-Pin Chen, Ssu-I Fu, Wen-Chau Liu, Shiou-Ying Cheng, Jung-Hui Tsai, Der-Feng Guo, and Wen-Shiung Lour

J. Appl. Phys. 101, 034501 (2007); http://dx.doi.org/10.1063/1.2432310 (5 pages) | Cited 4 times

Online Publication Date: 1 February 2007

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Specific treatments of the base surface of InGaP/GaAs heterojunction bipolar transistors are studied experimentally. The dual treatment method, based on the combination of ledge and sulfur passivation, shows better temperature-dependent characteristics including higher dc gain, lower saturation voltage, lower base-emitter junction turn on voltage, lower leakage current, lower collector and base current ideality factors nC and nB, and wider collector current operating regimes over the measured temperature range (300–400 K). Therefore, the dual surface treatment method provides promise for high-performance electronic applications.
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85.30.Pq Bipolar transistors
81.65.Rv Passivation

Cross-plane Seebeck coefficient of ErAs:InGaAs/InGaAlAs superlattices

Gehong Zeng, Joshua M. O. Zide, Woochul Kim, John E. Bowers, Arthur C. Gossard, Zhixi Bian, Yan Zhang, Ali Shakouri, Suzanne L. Singer, and Arun Majumdar

J. Appl. Phys. 101, 034502 (2007); http://dx.doi.org/10.1063/1.2433751 (5 pages) | Cited 15 times

Online Publication Date: 6 February 2007

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We characterize cross-plane and in-plane Seebeck coefficients for ErAs:InGaAs/InGaAlAs superlattices with different carrier concentrations using test patterns integrated with microheaters. The microheater creates a local temperature difference, and the cross-plane Seebeck coefficients of the superlattices are determined by a combination of experimental measurements and finite element simulations. The cross-plane Seebeck coefficients are compared to the in-plane Seebeck coefficients and a significant increase in the cross-plane Seebeck coefficient over the in-plane Seebeck coefficient is observed. Differences between cross-plane and in-plane Seebeck coefficients decrease as the carrier concentration increases, which is indicative of heterostructure thermionic emission in the cross-plane direction.
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73.63.-b Electronic transport in nanoscale materials and structures
72.20.Pa Thermoelectric and thermomagnetic effects
79.40.+z Thermionic emission

Flatband voltage shift of ruthenium gated stacks and its link with the formation of a thin ruthenium oxide layer at the ruthenium/dielectric interface

Z. Li, T. Schram, L. Pantisano, T. Conard, S. Van Elshocht, W. Deweerd, S. De Gendt, K. De Meyer, A. Stesmans, S. Shamuilia, V. V. Afanas’ev, A. Akheyar, D. P. Brunco, N. Yamada, and P. Lehnen

J. Appl. Phys. 101, 034503 (2007); http://dx.doi.org/10.1063/1.2429730 (9 pages) | Cited 7 times

Online Publication Date: 6 February 2007

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A systematic study about the flatband voltage (Vfb) shift of Ru gated metal-oxide-semiconductor stacks after thermal treatment in O2 has been performed. The dependence of the Vfb shift on the anneal time and temperature and the thickness of Ru was studied in detail, and a clear link between the Vfb shift and an oxygen diffusion process in Ru was observed. A high temperature thermal treatment of the devices prior to the O2 anneal has no significant impact on the Vfb shift. The Vfb shift is ascribed to the shift of metal gates’ work function, and is not intrinsic to HfO2 gated stacks as similar behavior was also observed on SiO2, from the combination of internal photoemission and conventional capacitance-voltage measurement. No similar Vfb shift was observed for TiN gated stacks and the Vfb shift seems to be more related to the properties of gate electrodes other than those of gate dielectrics. After thermal treatment in 18O2, from time-of-flight secondary ion mass spectrometry measurement, it was found that 18O penetrated through Ru and was incorporated at around the Ru/dielectric interface, which corresponded to the formation of an interfacial RuOx layer. The thin interfacial RuOx layer was found to have very similar properties as the ones of bulk RuO2 and the mechanism of its formation was discussed from thermodynamics and kinetics points of view. We believe that the formation of a thin RuOx layer at around the Ru/dielectric interface in O2 ambient is responsible for the increase of the Vfb for Ru gated stacks.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.30.+y Surface double layers, Schottky barriers, and work functions
68.35.Fx Diffusion; interface formation
61.72.Cc Kinetics of defect formation and annealing
79.60.Jv Interfaces; heterostructures; nanostructures
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Application of self-organization methods to current-induced magnetization dynamics of a single-domain ferromagnet

P. M. Gorley, P. P. Horley, V. K. Dugaev, J. Barnaś, and W. Dobrowolski

J. Appl. Phys. 101, 034504 (2007); http://dx.doi.org/10.1063/1.2433993 (11 pages) | Cited 3 times

Online Publication Date: 7 February 2007

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Magnetization dynamics of a single-domain ferromagnet is studied theoretically using the methods developed for self-organization phenomena. Time evolution of the magnetization is described by the Landau-Lifshitz-Gilbert equation with the spin-transfer torque included. The equilibrium and stationary states are investigated as a function of spin current and external magnetic field. The presented bifurcation diagram allows the margins of a neutral stability mode of the equilibrium and stationary states to be determined. An envelope equation for the magnetization switching is derived. The switching time Δτ between different states is found to be comparable to the half-width of the time derivative of the system energy, which allows the energy flow due to spin current and the magnetization switching velocity to be related. Dynamics of the phase states in external magnetic field and in the presence of spin current is analyzed using different methods of numerical analysis.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.60.Ch Domain walls and domain structure

Dopant characterization of fin field-effect transistor structures using scanning capacitance microscopy

A. A. Khajetoorians, J. Li, C. K. Shih, X.-D. Wang, D. Garcia-Gutierrez, M. Jose-Yacaman, D. Pham, H. Celio, and A. Diebold

J. Appl. Phys. 101, 034505 (2007); http://dx.doi.org/10.1063/1.2434000 (5 pages) | Cited 6 times

Online Publication Date: 9 February 2007

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Scanning capacitance microscopy studies of processed fin structures for fin field-effect transistor (FinFET) are presented. We characterized carrier profiling of fins as a function of implantation conditions. The results are confirmed by high angle annular dark field transmission electron microscopy study and qualitatively agree with simulations. The techniques we report can be used in conjunction with implantation and simulation to characterize the dopant profile of FinFET structures and further optimize FinFET processing parameters.
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61.72.S- Impurities in crystals
85.30.Tv Field effect devices
68.37.Lp Transmission electron microscopy (TEM)

Effect of channel positioning on the 1/f noise in silicon-on-insulator metal-oxide-semiconductor field-effect transistors

Martin von Haartman and Mikael Östling

J. Appl. Phys. 101, 034506 (2007); http://dx.doi.org/10.1063/1.2433772 (4 pages) | Cited 2 times

Online Publication Date: 13 February 2007

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p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on silicon-on-insulator (SOI) substrates with an ultrathin ( ∼ 20 nm) lightly p-doped Si body were found to show about an order of magnitude lower 1/f noise than that in conventional bulk Si pMOSFETs when biased in strong inversion. In order to investigate the origin of the 1/f noise and find an explanation for the 1/f noise reduction, the 1/f noise in the SOI devices was studied as a function of the back gate voltage. The 1/f noise was found to increase with increasing back gate voltage, which acts to push the carriers closer towards the front gate oxide interface. The average distance of the inversion carriers from the gate oxide interface was obtained from simulations and used to interpret the 1/f noise behavior. The Hooge parameter, extracted for several different 1/f noise experiments where one or two terminal voltages were varied, exhibited a general behavior similar for both the SOI and bulk Si pMOSFETs. The Hooge parameter was shown to increase markedly when the average carrier-oxide separation is around 2 nm. Possible explanations of the results were discussed in terms of the mobility fluctuation noise model.
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85.30.Tv Field effect devices
72.70.+m Noise processes and phenomena

Magnetostrictive bimagnetic trilayer ribbons for temperature sensing

P. Mendoza Zélis, F. Sánchez, and M. Vázquez

J. Appl. Phys. 101, 034507 (2007); http://dx.doi.org/10.1063/1.2422905 (6 pages) | Cited 8 times

Online Publication Date: 13 February 2007

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A magnetic biphase trilayer ribbon, consisting of a melt-spun FeSiB inner amorphous ribbon with positive magnetostriction coated by two electroplated nickel layers with negative magnetostriction, is here proposed as an element to be incorporated in temperature sensor devices. The inductance of a small coil wounded around the trilayer is characterized as the sensitive parameter. The dependence of coil’s inductance on the thickness of electroplated Ni has been evaluated in the range of measuring temperatures of 0–70 °C, and optimum electroplating parameters were determined. Magnetic characteristics are determined through the study of hysteresis loops, which denote the presence of the two magnetic phases. The experimental results are interpreted considering a simple magnetoelastic model taking into account the mechanical stresses arising from the different thermal expansion coefficients of each magnetic phase.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Bb Fe and its alloys
75.80.+q Magnetomechanical effects, magnetostriction
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
75.50.Kj Amorphous and quasicrystalline magnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Numerical investigation of transient capacitances of Ge/Si heteronanocrystal memories in retention mode

Yan Zhu, Dengtao Zhao, and Jianlin Liu

J. Appl. Phys. 101, 034508 (2007); http://dx.doi.org/10.1063/1.2434947 (4 pages) | Cited 4 times

Online Publication Date: 13 February 2007

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Transient capacitances were numerically investigated for Ge/Si heteronanocrystal memories. Flatband voltage shifts (ΔVfb) were obtained. The results suggest that the Ge/Si heteronanocrystal memories have significantly longer data retention compared with the memories embedding Si nanocrystals only. It is also found that larger heteronanocrystal leads to longer retention, larger device capacitance, and smaller ΔVfb.
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85.30.-z Semiconductor devices
84.30.Sk Pulse and digital circuits

Consequences of nonstochiometric SiOx interfacial layers on the electrical characterization of metal-oxide-semiconductor devices

J. S. de Sousa, P. F. R. Leite, Jr., E. L. de Oliveira, V. N. Freire, and G. A. Farias

J. Appl. Phys. 101, 034509 (2007); http://dx.doi.org/10.1063/1.2433998 (6 pages)

Online Publication Date: 14 February 2007

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We present a theoretical study of the role of nonstochiometric SiOx suboxides in the oxide-semiconductor interface of Si/SiO2 metal-oxide-semiconductor (MOS) devices. We show that nonabrupt SiOx layers and fluctuations in their localization imply: (i) Capacitance degradation for voltages above threshold, (ii) variations in the threshold voltage of the order of 20 mV, and (iii) errors in the determination of the effective oxide thickness by means of electrical measurements.
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85.30.Tv Field effect devices

Degradation mechanisms in organic light-emitting devices: Metal migration model versus unstable tris(8-hydroxyquinoline) aluminum cationic model

Yichun Luo, Hany Aziz, Zoran D. Popovic, and Gu Xu

J. Appl. Phys. 101, 034510 (2007); http://dx.doi.org/10.1063/1.2435070 (4 pages) | Cited 11 times

Online Publication Date: 14 February 2007

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To resolve the issue of which of the “indium migration” model and the “unstable AlQ3 cationic” model plays a more important role in luminescence degradation of organic light-emitting devices, we investigated the effect of the device structures on device operational stability. The results show that alterations in device layer structures can significantly affect the device operational stability, although they do not appear to noticeably change the magnitude of indium migrations. This suggests that the indium migration model may not play a dominant role in device degradation. On the other hand, the change in device stability with the alteration in the device structures can be plausibly explained by the unstable AlQ3 cationic model.
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85.60.Jb Light-emitting devices
85.30.De Semiconductor-device characterization, design, and modeling

Permanent-magnet longitudinal fields for magnetostrictive devices

Tianli Zhang, Chengbao Jiang, Huibin Xu, and Jianqin Mao

J. Appl. Phys. 101, 034511 (2007); http://dx.doi.org/10.1063/1.2435809 (3 pages) | Cited 2 times

Online Publication Date: 14 February 2007

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This paper discusses a technique for improving the homogeneity of the magnetic field of tube-like permanent magnets designed for magnetostrictive devices. The high homogeneity of the magnetic field along the tube is achieved by gradually changing shape or remanence of combined short rings. The analysis of the field in the magnet is performed using the magnetic charge principle and axial magnetic field equations are deduced. An example of design of a longitudinal uniform field for a magnetostrictive rod with large length to diameter ratio is presented.
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75.50.Ww Permanent magnets
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.80.+q Magnetomechanical effects, magnetostriction
85.70.Ec Magnetostrictive, magnetoacoustic, and magnetostatic devices

A hybrid method for calorimetry with subnanoliter samples using Schottky junctions

T. K. Hakala, J. J. Toppari, and P. Törmä

J. Appl. Phys. 101, 034512 (2007); http://dx.doi.org/10.1063/1.2436929 (5 pages) | Cited 1 time

Online Publication Date: 15 February 2007

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A μm-scale calorimeter realized by using Schottky junctions as a thermometer is presented. Combined with a hybrid experimental method, it enables simultaneous time-resolved measurements of variations in both the energy and the heat capacity of subnanoliter samples.
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07.20.Fw Calorimeters
07.20.Dt Thermometers
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