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12 Feb 1990

Volume 56, Issue 7, pp. 599-697

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Buried‐ridge striped planar GaAlAs/GaAs lasers with a wide range of effective index steps

Song Jae Lee, Ramu V. Ramaswamy, Peter S. Zory, and Luis Figueroa

Appl. Phys. Lett. 56, 599 (1990); http://dx.doi.org/10.1063/1.102732 (3 pages) | Cited 2 times

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A novel self‐aligned buried‐ridge striped planar (BRSP) GaAlAs/GaAs diode laser structure is presented. The structure was grown by two‐step liquid phase epitaxy using preferential growth and melt etch. A Ga1−y Aly As layer with a wide range of Al concentration (y>0.05) is selectively grown outside the ridge and can be an effective melt‐etching mask. As a result, the BRSP structure can incorporate virtually all effective index steps, i.e., the positive, negative, and complex index steps. The threshold current of the BRSP structure is between 70 and 100 mA. The BRSP structure may prove to be of importance in the realization of linear array lasers.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
42.60.By Design of specific laser systems

All‐optical tuning of waveguide nonlinear distributed feedback gratings

J. E. Ehrlich, G. Assanto, and G. I. Stegeman

Appl. Phys. Lett. 56, 602 (1990); http://dx.doi.org/10.1063/1.102710 (3 pages) | Cited 15 times

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The nonlinear properties of a distributed feedback grating in a waveguide characterized by a diffusive thermal nonlinearity were investigated experimentally. Reflection and transmission were measured in an InSb planar structure, and all‐optical tuning of the reflectivity was achieved either by a guided wave incident onto the distributed feedback grating near its Bragg condition, or by a second guided beam tuned far from the Bragg condition.
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42.82.-m Integrated optics
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.79.Dj Gratings
42.79.Gn Optical waveguides and couplers

Electro‐optical multistability in GaAs/AlAs superlattices at room temperature

H. Schneider, K. Fujiwara, H. T. Grahn, K. v. Klitzing, and K. Ploog

Appl. Phys. Lett. 56, 605 (1990); http://dx.doi.org/10.1063/1.102711 (3 pages) | Cited 33 times

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We have studied the optical absorption properties of a GaAs/AlAs short‐period superlattice at room temperature in an electric field perpendicular to the layers. Several pronounced optical transitions related to Wannier–Stark localization are observed indicating a coherence length of at least five superlattice periods. These transitions produce multiple regions of negative differential photoconductivity which are used to realize a multistable self‐electro‐optic effect device.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects

Nd:CaYAlO4—a new crystal for solid‐state lasers emitting at 1.08 μm

Horacio R. Verdún and Leonard M. Thomas

Appl. Phys. Lett. 56, 608 (1990); http://dx.doi.org/10.1063/1.102712 (3 pages) | Cited 24 times

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Crystals with the K2 NiF4 structure are good hosts for transition metal and rare‐earth ions. Continuous‐wave room‐temperature laser action in a neodymium‐doped crystal with this structure, CaYAlO4 , was observed using a GaAlAs diode laser array for end pumping of the laser rod. The free‐running laser operated at a wavelength of 1080.6 nm.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.45.+h Stimulated emission

Gain nonlinearities in semiconductor lasers and amplifiers

Alfred P. DeFonzo and B. Gomatam

Appl. Phys. Lett. 56, 611 (1990); http://dx.doi.org/10.1063/1.102713 (3 pages) | Cited 5 times

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A concise and fundamentally straightforward physical model that accounts for the nonlinear gain in both semiconductor amplifiers and lasers is presented. Calculations based on this model yield results that agree very well with observed transient gain recovery dynamics in semiconductor laser amplifiers. The value of the symmetric steady‐state gain suppression factor is found to be β=1.67×10−23 m3 in good agreement with experiment. The model accounts for a wavelength dependence of the asymmetric part of the nonlinear gain observed in direct mixing experiments observed in semiconductor lasers.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
85.30.De Semiconductor-device characterization, design, and modeling

Self‐induced transparency soliton digital switch

A. Guzmàn, M. Romagnoli, and S. Wabnitz

Appl. Phys. Lett. 56, 614 (1990); http://dx.doi.org/10.1063/1.102714 (3 pages) | Cited 9 times

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We investigate self‐induced transparency soliton switching in a nonlinear two‐level resonant dual‐waveguide directional coupler. The soliton transfer properties of the coupler depend on the input pulse area; for areas larger than π, an integer number of 2π solitons is transmitted from the output ports. Tapered coupling provides digital transmission characteristics. A specific example of application to impurity bound excitons in semiconductors is discussed.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
07.60.-j Optical instruments and equipment
42.79.-e Optical elements, devices, and systems
78.55.Cr III-V semiconductors
85.60.Jb Light-emitting devices

Lorentz force and magnetic stress in force‐free configurations

N. A. Salingaros

Appl. Phys. Lett. 56, 617 (1990); http://dx.doi.org/10.1063/1.102715 (3 pages) | Cited 9 times

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Special current distributions that are widely assumed to have vanishing self‐force in fact can have sizable magnetic forces. The Lorentz self‐force is often miscomputed by ignoring part of the magnetic self‐field in the traditional model of force‐free configurations. Furthermore, magnetic stresses in general do not vanish when the Lorentz force does. These stresses are responsible for the observed deformation of Lorentz force‐free electromagnets. Although straightforward, these results revise some long‐established models in superconducting magnet design, magnetic confinement fusion, and astrophysical magnetic fields.
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41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
52.55.Dy General theory and basic studies of plasma lifetime, particle and heat loss, energy balance, field structure, etc.
84.71.Ba Superconducting magnets; magnetic levitation devices

Bias‐controlled chemical vapor deposition of diamond thin films

Y. H. Lee, P. D. Richard, K. J. Bachmann, and J. T. Glass

Appl. Phys. Lett. 56, 620 (1990); http://dx.doi.org/10.1063/1.102716 (3 pages) | Cited 20 times

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The growth of diamond films on (001) Si substrates by bias‐controlled chemical vapor deposition is described. The film quality as judged by Raman spectroscopy and scanning electron microscopy depends strongly on the biasing conditions. Under low current reverse bias conditions, highly facetted cubo‐octahedral diamond growth exhibiting a single sharp Raman line at 1332 cm−1 was obtained, while biasing in high current conditions which created a plasma resulted in multiply twinned, microcrystalline growth incorporating sp2‐bonded carbon into the diamond film.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology

A 27.3% efficient Ga0.5In0.5P/GaAs tandem solar cell

J. M. Olson, S. R. Kurtz, A. E. Kibbler, and P. Faine

Appl. Phys. Lett. 56, 623 (1990); http://dx.doi.org/10.1063/1.102717 (3 pages) | Cited 97 times

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A two‐terminal, monolithic cascade solar cell with an efficiency of 27.3% is reported. The device structure consists of a Ga0.5In0.5P homojunction grown epitaxially upon a GaAs homojunction, with a GaAs tunnel diode interconnect. The tandem combination of these two materials is lattice matched, and has a theoretical efficiency of 34%. The device was grown by metalorganic chemical vapor deposition at 700 °C, using trimethylgallium, trimethylindium, arsine, and phosphine as sources. The minority‐carrier transport properties of the Ga0.5In0.5P are shown to be relatively insensitive to variations of the growth temperature and phosphine overpressure. Other factors that affect the efficiency of the device are presented and discussed.
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84.60.Jt Photoelectric conversion
72.40.+w Photoconduction and photovoltaic effects
85.30.De Semiconductor-device characterization, design, and modeling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Stimulated emission from monolayer‐thick AlxGa1−xAs‐GaAs single quantum well heterostructures

J. H. Lee, K. Y. Hsieh, Y. L. Hwang, and R. M. Kolbas

Appl. Phys. Lett. 56, 626 (1990); http://dx.doi.org/10.1063/1.102718 (3 pages) | Cited 4 times

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Stimulated emission from a clearly defined quantum well transition has been observed from single quantum wells as thin as two monolayers (ML, 1 ML=2.83 Å). These results are unexpected since previous experimental and theoretical work has indicated that if the well width Lz is smaller than the scattering path length of electrons or holes, carrier collection becomes inefficient and the quantum well cannot support stimulated emission. Laser thresholds of these separate confinement, single quantum well samples are quite low, despite the fact that these ultrathin quantum wells are undoped and do not have graded band‐gap confining layers. These unexpected results can be explained in terms of the spatial extent of the wave function rather than the well thickness.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.45.+h Stimulated emission
71.23.An Theories and models; localized states

Kinetics of silicon epitaxy using SiH4 in a rapid thermal chemical vapor deposition reactor

M. Liehr, C. M. Greenlief, S. R. Kasi, and M. Offenberg

Appl. Phys. Lett. 56, 629 (1990); http://dx.doi.org/10.1063/1.102719 (3 pages) | Cited 64 times

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The equilibrium hydrogen surface coverage on Si(100) during silicon epitaxy using SiH4 has been measured in a rapid thermal chemical vapor deposition reactor. The hydrogen coverage could be ‘‘frozen out’’ completely on the surface by a rapid cool‐down and pump‐down of the reactor up to temperatures of ≂575 °C; at temperatures above 575 °C only partial ‘‘freeze‐out’’ is achieved. Surface hydrogen was titrated in situ using the reactor as a thermal desorption spectrometer. Epitaxial silicon films were grown in the temperature range 450–700 °C and the film growth kinetics was correlated with the equilibrium hydrogen coverage. The growth mechanism changes from the low‐temperature regime, where the surface is hydrogen covered, to the high‐temperature regime, where the surface is essentially clean.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Electron‐hole transition energies and atomic steps at the interfaces of thin InGaAs/InP quantum wells

M. Zachau and D. Grützmacher

Appl. Phys. Lett. 56, 632 (1990); http://dx.doi.org/10.1063/1.102720 (3 pages) | Cited 5 times

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We measure the absorption of thin InGaAs/InP quantum wells with a well width between 0 and 20 Å. The discretization of the transition energies due to the quantization of the well width by monolayers is clearly observed for both the heavy and light hole excitons. The dependences of the heavy and light hole transition energies on the InGaAs growth time are investigated and show striking differences. This is discussed in relation to the atomic steps at the interfaces of the wells. The measured heavy and light hole transition energies agree well with calculation, which takes the split‐off holes into account.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Silicon etching with oxygen molecular beam assisted by predeposited germanium

Toru Tatsumi, Taeko Niino, and Hiroyuki Hirayama

Appl. Phys. Lett. 56, 635 (1990); http://dx.doi.org/10.1063/1.102721 (3 pages) | Cited 1 time

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Si was etched using an O2 molecular beam according to the chemical reaction 2Si+O2→2SiO↑. The minimum etching temperature was decreased by 25 °C when a Ge layer had been deposited on a clean Si surface before etching. At 800 °C, the Ge‐coated Si surface was etched while the clean Si surface was not. The O2 partial pressure during etching was 2×10−5 Torr; the etching rate was about 80 Å/min at 800 °C. Auger electron spectroscopy showed that the number of Ge atoms slightly decreased during Si etching. Ge atoms on the surface are thought to weaken Si back bonds by forming a thin Ge‐Si alloy layer on the surface. Undercutting at the SiO2 mask edge was suppressed by this Ge predeposition technique at 800 °C because the sidewall without Ge was not etched at this temperature.
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81.65.-b Surface treatments
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Infrared absorption spectra in bulk Fe‐doped InP

R. Fornari and J. Kumar

Appl. Phys. Lett. 56, 638 (1990); http://dx.doi.org/10.1063/1.102722 (3 pages) | Cited 24 times

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We have observed that the absorption spectra in bulk Fe‐doped indium phosphide differ considerably from those recorded on undoped and n‐type samples. In the former case it was seen that the absorption edge presents a tail whose shape depends on the concentration of iron atoms incorporated into the matrix. Based on this phenomenon, we present a new nondestructive method which can be successfully employed to measure the iron concentration in semi‐insulating InP.
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78.30.Fs III-V and II-VI semiconductors
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.55.Eq III-V semiconductors

Effects of hydrogen on Al/p‐Si Schottky barrier diodes

Y. Q. Jia and G. G. Qin

Appl. Phys. Lett. 56, 641 (1990); http://dx.doi.org/10.1063/1.102723 (3 pages) | Cited 11 times

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Hydrogen was incorporated into B‐doped p‐type crystalline silicon in three different ways: boiling the sample in water, exposing the sample to hydrogen plasma, growing silicon in a hydrogen atmosphere. Al‐contact Schottky barrier diodes were made on both the hydrogenated and unhydrogenated samples. It was found that the Schottky barrier height (SBH) is increased due to the hydrogenation. The current‐voltage measurement showed an increase of 0.06–0.10 eV in the effective SBH and the activation energy measurement revealed an increase of 0.07–0.09 eV in the SBH under a forward bias of 0.15 V. If the silicon grown in a hydrogen atmosphere was thermal annealed at 650 °C to drive out hydrogen before Schottky metallization, then the SBH approached that of the unhydrogenated sample. It is demonstrated that the SBH in Al/p‐Si can be increased with hydrogen incorporated in silicon.
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81.40.Rs Electrical and magnetic properties related to treatment conditions
73.30.+y Surface double layers, Schottky barriers, and work functions
85.30.Hi Surface barrier, boundary, and point contact devices
73.40.Ns Metal-nonmetal contacts

Dark current and diffusion length in InGaAs photodiodes grown on GaAs substrates

E. Ishimura, T. Kimura, T. Shiba, Y. Mihashi, and H. Namizaki

Appl. Phys. Lett. 56, 644 (1990); http://dx.doi.org/10.1063/1.102724 (3 pages) | Cited 8 times

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In0.53Ga0.47As photodiodes grown on GaAs substrates have been fabricated and analyzed. The dislocation density in the InGaAs layer is 2×107 cm−2. A lowest dark current of 3.8×10−4 A/cm2 at 10 V bias is obtained, which is very stable during a bias‐temperature test of Vb=−10 V, T=175 °C, and t=100 h. The quantum efficiency is more than 85% at λ=1.3 μm. This device is expected to be practically used. The dark current has been successfully explained by the thermionic emission and thermionic field emission from traps at midgap. The diffusion length of holes in the InGaAs layer is explained by the recombination at dislocations with the finite recombination velocity of S∼104 cm/s.
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85.60.Dw Photodiodes; phototransistors; photoresistors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
72.40.+w Photoconduction and photovoltaic effects

Quantitative, all‐optical prediction of the carrier density in semi‐insulating GaAs

T. W. Steiner, Yu. Zhang, M. L. W. Thewalt, M. Maciaszek, and R. P. Bult

Appl. Phys. Lett. 56, 647 (1990); http://dx.doi.org/10.1063/1.102725 (3 pages) | Cited 5 times

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We have used a series of all‐optical measurements to determine shallow acceptor, shallow donor, and midgap donor (EL2) concentrations. The validity of these measurements was then tested by comparing the predicted electron density to the measured Hall density. Resonant pumping of the first excited state of the polariton sharpened the photoluminescence spectrum sufficiently to allow a reliable measurement of the shallow donor to acceptor ratio. The absolute shallow acceptor, donor, and EL2 concentrations were determined by a series of absorption and luminescence measurements. The Fermi level and hence the carrier concentration was then deduced using the three‐level model of semi‐insulating behavior.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.80.Ey III-V and II-VI semiconductors
78.55.Cr III-V semiconductors
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors

Amorphous silicon phototransistors

Yoshiyuki Kaneko, Norio Koike, Ken Tsutsui, and Toshihisa Tsukada

Appl. Phys. Lett. 56, 650 (1990); http://dx.doi.org/10.1063/1.102726 (3 pages) | Cited 22 times

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An amorphous silicon field‐effect phototransistor is fabricated using a processing technology compatible with conventional amorphous silicon‐silicon nitride thin‐film transistors. The phototransistor has an offset structure between the source and gate electrodes, where light is absorbed to produce a photocurrent. In an electron accumulation mode, the photocurrent is greater than the dark current by three orders of magnitude. In addition, the phototransistor is found to have output characteristics showing good saturation. Typical photoconductive gain of this saturation current is 17.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.Tv Field effect devices
73.50.Pz Photoconduction and photovoltaic effects
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Monte Carlo analysis of ionization threshold in Si

Nobuyuki Sano, Masaaki Tomizawa, and Akira Yoshii

Appl. Phys. Lett. 56, 653 (1990); http://dx.doi.org/10.1063/1.102727 (3 pages) | Cited 10 times

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Monte Carlo simulations of electronic high‐field transport in Si are performed. Contrary to previous treatments of impact ionization, we do not employ the ordinary Keldysh formula [Sov. Phys. JETP 21, 1135 (1965)] with a soft threshold, but rather a new expression, which is an explicit function of the wave vector of the initiating electron, is used. The calculation results of drift velocity, ionization coefficient, and quantum yield show excellent agreement with the experimental data. Our results strongly substantiate the idea that the ionization threshold is basically hard even in Si in the sense that the electrons rapidly ionize when they approach the threshold energies and that the softness of the ionization threshold is introduced through the wave vector dependence of the threshold energies.
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79.20.Hx Electron impact: secondary emission
72.20.Ht High-field and nonlinear effects
72.80.Cw Elemental semiconductors

Ideal hydrogen termination of the Si (111) surface

G. S. Higashi, Y. J. Chabal, G. W. Trucks, and Krishnan Raghavachari

Appl. Phys. Lett. 56, 656 (1990); http://dx.doi.org/10.1063/1.102728 (3 pages) | Cited 676 times

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Aqueous HF etching of silicon surfaces results in the removal of the surface oxide and leaves behind silicon surfaces terminated by atomic hydrogen. The effect of varying the solution pH on the surface structure is studied by measuring the SiH stretch vibrations with infrared absorption spectroscopy. Basic solutions ( pH=9–10) produce ideally terminated Si(111) surfaces with silicon monohydride ( 3/4 SiH) oriented normal to the surface. The surface is found to be very homogeneous with low defect density (<0.5%) and narrow vibrational linewidth (0.95 cm−1 ).
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73.20.At Surface states, band structure, electron density of states
68.35.Dv Composition, segregation; defects and impurities
81.65.-b Surface treatments
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors

Direct demonstration of a misfit strain‐generated electric field in a [111] growth axis zinc‐blende heterostructure

E. A. Caridi, T. Y. Chang, K. W. Goossen, and L. F. Eastman

Appl. Phys. Lett. 56, 659 (1990); http://dx.doi.org/10.1063/1.102729 (3 pages) | Cited 130 times

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We report the first direct demonstration of a strain‐generated built‐in electric field in a (111) oriented strained‐layer heterostructure. We present a model which describes the accommodation of the misfit strain in a lattice‐mismatched quantum well, and the resulting generation of a longitudinal electric field via the piezoelectric effect. On a (111)B GaAs substrate, we grew the quantum well in the intrinsic region of a p‐i‐n diode such that the strain‐generated electric field in the quantum well opposes the weaker built‐in electric field of the diode. Under reverse bias operation, photoconductivity measurements show a quadratic blue shift of the quantum well electroabsorption peaks, in contrast to the red shifts normally observed in the quantum‐confined Stark effect. The measured blue shifts demonstrate an electric field strength of 1.7×105 V/cm, which agrees with theory to within the accuracy of the measured sample characteristics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Pz Photoconduction and photovoltaic effects
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
68.35.Gy Mechanical properties; surface strains

Band‐gap narrowing in ordered and disordered semiconductor alloys

S.‐H. Wei and Alex Zunger

Appl. Phys. Lett. 56, 662 (1990); http://dx.doi.org/10.1063/1.103307 (3 pages) | Cited 158 times

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Either spontaneous or artificial ordering of semiconductor alloys into CuAu‐like, chalcopyrite, or CuPt‐like structures is predicted to be accompanied by a reduction in the direct band gaps relative to the average over the binaries. In this letter calculated results are presented for seven III‐V and II‐VI alloys. We identify the mechanism for this band‐gap narrowing as band folding followed by repulsion between the folded states. The latter is coupled by the non‐zinc‐blende component of the superlattice potential. The same physical mechanism (but to a different extent) is responsible for gap bowing in disordered alloys.
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71.55.Eq III-V semiconductors
71.55.Gs II-VI semiconductors
71.70.-d Level splitting and interactions

Electronic analog of the electro‐optic modulator

Supriyo Datta and Biswajit Das

Appl. Phys. Lett. 56, 665 (1990); http://dx.doi.org/10.1063/1.102730 (3 pages) | Cited 1672 times

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We propose an electron wave analog of the electro‐optic light modulator. The current modulation in the proposed structure arises from spin precession due to the spin‐orbit coupling in narrow‐gap semiconductors, while magnetized contacts are used to preferentially inject and detect specific spin orientations. This structure may exhibit significant current modulation despite multiple modes, elevated temperatures, or a large applied bias.
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85.30.Tv Field effect devices
42.79.Hp Optical processors, correlators, and modulators
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Surface and interface free‐carrier depletion in GaAs molecular beam epitaxial layers: Demonstration of high interface charge

D. C. Look, C. E. Stutz, and K. R. Evans

Appl. Phys. Lett. 56, 668 (1990); http://dx.doi.org/10.1063/1.102731 (3 pages) | Cited 10 times

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Molecular beam epitaxial GaAs layers of electron concentration 1.69×1017 cm−3, and various thicknesses d=0.25, 0.50, 1.00, and 2.00 μm, have been grown on semi‐insulating GaAs substrates and characterized by the Hall effect and capacitance‐voltage (C‐V) techniques. A plot of sheet Hall concentration ns vs d gives accurate values of (ND−NA) and (ws+wi), the sum of the surface and interface free‐carrier depletion widths, respectively. The C‐V measurements verify the value of ND−NA, and also give a good estimate of wi. By comparing the value of wi with depletion theory, it is shown unambiguously that the interface depletion is mainly due to interface states, of concentration 1.2×1012 cm−2 (below midgap). This result has important technological implications.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
68.55.-a Thin film structure and morphology
73.50.-h Electronic transport phenomena in thin films

Reaction and stability of metal/silicide interfaces: Ti/MoSi2 (001)

J. P. Sullivan, Toshiyuki Hirano, T. Komeda, H. M. Meyer, B. M. Trafas, G. D. Waddill, and J. H. Weaver

Appl. Phys. Lett. 56, 671 (1990); http://dx.doi.org/10.1063/1.103308 (3 pages) | Cited 3 times

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Metal/single‐crystal‐silicide interface evolution has been examined for Ti/MoSi2 (001) using high‐resolution synchrotron radiation and x‐ray photoemission. Reaction between Ti and Si was observed for temperatures 300≤T≤873 K. At 300 K, it was limited to Ti interaction with the single Si layer terminating the cleaved MoSi2 (001) surface. Analysis of the Si 2p core level line shape showed two different interfacial reaction products with bonding characteristics of TiSi and a disordered solution of Si in Ti. Interfacial development was dominated by Si outdiffusion at higher temperatures with Si enrichment of the overlayer but not conversion to a silicide.
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68.35.Fx Diffusion; interface formation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
73.40.Ns Metal-nonmetal contacts
73.20.At Surface states, band structure, electron density of states
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