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11 Nov 1996

Volume 69, Issue 20, pp. 2953-3103

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Study of nonlinear optical effects in GaN:Mg epitaxial film

H. Y. Zhang, X. H. He, Y. H. Shih, M. Schurman, Z. C. Feng, and R. A. Stall

Appl. Phys. Lett. 69, 2953 (1996); http://dx.doi.org/10.1063/1.117741 (3 pages) | Cited 31 times

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The second‐order nonlinear optical coefficients d33, d31, and d15 of GaN:Mg epitaxial film were studied by the standard Maker fringe of an anisotropic medium. The measured d33=−(16.5±1.3) pm/V which is 55 times of the d11 of quartz. The measured ratios of d33/d31 and d31/d15 showed that the crystalline film is close to an ideal wurzite structure. The refractive indices and the dispersive curves of ne, n0 were also determined by TM and TE waveguide mode measurements. © 1996 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.66.Fd III-V semiconductors
42.65.-k Nonlinear optics

Controlled electroluminescence spectra of porous silicon diodes with a vertical optical cavity

Minoru Araki, Hideki Koyama, and Nobuyoshi Koshida

Appl. Phys. Lett. 69, 2956 (1996); http://dx.doi.org/10.1063/1.117742 (3 pages) | Cited 24 times

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It is demonstrated that a porous silicon (PS) optical cavity is available for the electroluminescence (EL) PS diode configuration. The PS diode is composed of a thin Au film, a light‐emitting PS layer, a multilayered PS mirror, a p‐type Si substrate, and an ohmic contact. When a sufficient bias voltage is applied to the diode, a uniform visible light emission is observed through the top contact. The EL intensity is fairly proportional to the driving current over a wide range of operation. The bandwidth of the EL spectrum is significantly reduced in comparison to that of the conventional PS diodes, owing to a resonance effect induced between the Au film and the multilayered PS mirror. These results suggest that the PS technology is a promising process for applications in monolithic integrated optoelectronics. © 1996 American Institute of Physics.
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42.82.-m Integrated optics
78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices
78.66.Db Elemental semiconductors and insulators

Color‐tunable organic light‐emitting devices

P. E. Burrows, S. R. Forrest, S. P. Sibley, and M. E. Thompson

Appl. Phys. Lett. 69, 2959 (1996); http://dx.doi.org/10.1063/1.117743 (3 pages) | Cited 96 times

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We demonstrate an integrated, two‐color organic light‐emitting device for flat‐panel display applications. The device utilizes a unique stacked pixel architecture which allows for independent tuning of color and intensity. Each of the two addressable colors is sufficiently bright for video display applications, so that the compact stacked pixel, which maximizes display resolution, may form the basis of a new type of full‐color display. © 1996 American Institute of Physics.
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42.70.Jk Polymers and organics
42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems

High electric field conduction mechanisms in electrode poling of electro‐optic polymers

Martin Sprave, Robert Blum, and Manfred Eich

Appl. Phys. Lett. 69, 2962 (1996); http://dx.doi.org/10.1063/1.117744 (3 pages) | Cited 17 times

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We investigated electrical conduction phenomena, which occurred during high electric field electrode poling of side chain χ(2) polymers. Electric current and second harmonic intensity were measured simultaneously in poling experiments performed on samples with and without an additional inorganic poly–methyl–siloxane layer. Current densities appeared to be limited by a Schottky‐type potential barrier at the electrode/insulator interface. The field dependence of the current density was found to be Schottky charge emission for medium field strengths (EPOL≤100 V/μm) whereas it was dominated by Fowler–Nordheim tunneling at higher poling fields. In the presence of the siloxane layer, a significant suppression of tunneling current was observed. This leads to a reduced probability of singular dielectric breakdown events and shifts the limit of avalanche breakdown to higher internal effective poling field strengths. © 1996 American Institute of Physics.
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42.70.Jk Polymers and organics
72.80.Le Polymers; organic compounds (including organic semiconductors)
72.20.Ht High-field and nonlinear effects
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Valence band spectroscopy in V‐grooved quantum wires

G. Goldoni, F. Rossi, E. Molinari, A. Fasolino, R. Rinaldi, and R. Cingolani

Appl. Phys. Lett. 69, 2965 (1996); http://dx.doi.org/10.1063/1.117745 (3 pages) | Cited 21 times

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We present a combined theoretical and experimental study of the anisotropy in the optical absorption of V‐shaped quantum wires. By means of realistic band structure calculations for these structures, we show that detailed information on the heavy‐ and light‐hole states can be singled out from the anisotropy spectra independently of the electron confinement, thus allowing accurate valence band spectroscopy. © 1996 American Institute of Physics.
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78.66.Fd III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Thin film channel waveguides fabricated in metalorganic chemical vapor deposition grown BaTiO3 on MgO

D. M. Gill, B. A. Block, C. W. Conrad, B. W. Wessels, and S. T. Ho

Appl. Phys. Lett. 69, 2968 (1996); http://dx.doi.org/10.1063/1.117746 (3 pages) | Cited 40 times

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We report on the fabrication of channel waveguides in epitaxial grown BaTiO3 layers on MgO. Layers were prepared by metalorganic chemical vapor deposition. Ridge waveguides with ridge heights ranging from 15 to 200 nm were fabricated in a 0.2‐μm‐thick film. Single mode waveguide throughput, scattering loss, and mode profiles are reported. Coating waveguides with spin on glass significantly increase waveguide throughput. Throughputs of up to 10.4% were measured in 15 nm ridge waveguides which were 2.85 mm long and coated with spin on glass. Waveguide throughput is found to increase significantly with an increase in wavelength from 1.06 to 1.55 μm. © 1996 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Effect of plasticization of dye doped polymer on second‐order optical nonlinearity induced by electric field

Takashi Sugihara, Kouji Fujii, Hiroshi Haga, and Sadahiko Yamamoto

Appl. Phys. Lett. 69, 2971 (1996); http://dx.doi.org/10.1063/1.117747 (3 pages) | Cited 3 times

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The nonlinear molecules dispersed in the polymer with low glass transition temperature (Tg) can be easily reoriented. The plasticizer is utilized in order to lower the Tg of the polymer matrix. We measured the frequency responses of second‐harmonic generation in a dye doped plasticized polymer to clarify the electric field dependence of the second‐order optical nonlinearity. We utilize poly(methyl methacrylate) doped with 2‐methyl‐4‐nitroaniline as the dye doped polymer. di(ethyl‐2 hexyl) phthalate is used as the plasticizer. The experimental results show that the rotational mobility was enhanced up to ten times by a DOP dose of 13.5 wt% in comparison with a dose of 0 wt% at 20°C. Therefore, this method is useful to increase the controllability of the optical nonlinearity by the electric field at room temperature. © 1996 American Institute of Physics.
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42.65.An Optical susceptibility, hyperpolarizability
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Jk Polymers and organics

Measurement of the mean electron‐hole pair creation energy in crystalline silicon for photons in the 50–1500 eV spectral range

F. Scholze, H. Rabus, and G. Ulm

Appl. Phys. Lett. 69, 2974 (1996); http://dx.doi.org/10.1063/1.117748 (3 pages) | Cited 14 times

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This letter reports a measurement of the mean electron‐hole pair creation energy in crystalline silicon using photons in the 50–1500 eV spectral range. A cryogenic electrical substitution radiometer in combination with monochromatized synchrotron radiation was used to determine the spectral responsivity of silicon photodiodes in this spectral range with a relative uncertainty of less than 0.3%. The mean electron‐hole pair creation energy has been determined from these measurements and in contrast to recent theoretical and experimental results a constant value of (3.64±0.03) eV was obtained in accordance with a calculation presented here. © 1996 American Institute of Physics.
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42.79.Pw Imaging detectors and sensors
85.60.Dw Photodiodes; phototransistors; photoresistors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Pz Photoconduction and photovoltaic effects

Characterization of Nd:Y3Al5O12 thin films grown on various substrates by pulsed laser deposition

Mizunori Ezaki, Minoru Obara, Hiroshi Kumagai, and Koichi Toyoda

Appl. Phys. Lett. 69, 2977 (1996); http://dx.doi.org/10.1063/1.117749 (3 pages) | Cited 15 times

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Epitaxial Nd‐doped yttrium aluminum garnet (NdxY3−xAl5O12 or Nd:YAG) films have been grown on various substrates by pulsed laser deposition for the purpose of fabricating diode‐pumped waveguide lasers. The films were characterized by Rutherford backscattering, x‐ray diffraction, atomic force microscopy, and photoluminescence measurements. Nd:YAG films on (100) silicon substrate with a large lattice mismatch show oriented stoichiometric growth. On the other hand, Nd:YAG films on garnet substrates (Nd undoped Gd3Ga5O12,Y3Al5O12 and Zr‐, Sc‐doped Gd3Ga5O12) show epitaxial growth with smooth surfaces. The optical properties of Nd‐doped YAG thin films on various substrates were comparable to those of Nd:YAG bulk laser crystal. © 1996 American Institute of Physics.
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42.70.Hj Laser materials
81.15.Fg Pulsed laser ablation deposition
78.66.Nk Insulators
68.55.-a Thin film structure and morphology

Reversible transition between transparency and opacity for the porous silica host dispersed with silver nanometer particles within its pores

Weiping Cai, Ming Tan, Guozhong Wang, and Lide Zhang

Appl. Phys. Lett. 69, 2980 (1996); http://dx.doi.org/10.1063/1.117750 (3 pages) | Cited 19 times

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The porous silica dispersed with silver nanometer particles (about 3 nm) within its pores (cages) has been prepared by a new method. In the process of alternative exposure to the ambient air and annealing, this material assumes reversible transition between transparency and opacity. This can be explained by oxidation of the outer part of the Ag particles during exposure to the ambient air and dissociation of the oxide during annealing in air. © 1996 American Institute of Physics.
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81.05.Rm Porous materials; granular materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)

Optical losses of Al‐free lasers for λ=0.808 and 0.98 μm

H. Yi, J. Diaz, B. Lane, and M. Razeghi

Appl. Phys. Lett. 69, 2983 (1996); http://dx.doi.org/10.1063/1.117751 (3 pages) | Cited 10 times

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In this work, we study the origin of the optical losses in Al‐free InGaAsP/GaAs (λ=0.808 μm) and InGaAs/GaAs/InGaP (λ=0.980 μm) lasers. Theoretical modeling and the experimental results indicate that the scattering of the laser beam by refractive index fluctuation in the alloys is the dominant loss in our lasers, and the loss due to the free‐carrier absorption and scattering by interface roughness are negligible. © 1996 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Remote infrared radiation detection using piezoresistive microcantilevers

P. G. Datskos, P. I. Oden, T. Thundat, E. A. Wachter, R. J. Warmack, and S. R. Hunter

Appl. Phys. Lett. 69, 2986 (1996); http://dx.doi.org/10.1063/1.117752 (3 pages) | Cited 32 times

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A novel micromechanical infrared (IR) radiation sensor has been developed using commercially available piezoresistive microcantilevers. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress between the top layer (coating) and the substrate. The bending causes a change in the piezoresistance and is proportional to the amount of heat absorbed. The microcantilever IR sensor exhibits two distinct thermal responses: a fast one (<ms) and a slower one (∼10 ms). A noise equivalent power (at a modulation frequency of 30 Hz) was estimated to be ∼70 nW/Hz1/2. This value can be further reduced by designing microcantilevers with better thermal isolation that can allow microcantilevers to be used as uncooled IR radiation detectors. © 1996 American Institute of Physics.
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07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.10.Cm Micromechanical devices and systems

Extremely high‐frequency self‐pulsations in chirped‐grating distributed‐feedback semiconductor lasers

Yuan‐Hwang Liao and Herbert G. Winful

Appl. Phys. Lett. 69, 2989 (1996); http://dx.doi.org/10.1063/1.117753 (3 pages) | Cited 2 times

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We show that an asymmetrically chirped, single‐section distributed‐feedback (DFB) laser is capable of sustained self‐pulsations at frequencies in excess of 200 GHz. These pulsations arise from mode beating and are absent in uniform or symmetrically chirped DFB lasers. For sufficiently large coupling constants, the pulsation frequency can approach a terahertz. © 1996 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Mi Dynamical laser instabilities; noisy laser behavior

Temporal evolution of soft x‐ray pulse emitted from aluminum plasma produced by a pair of Ti:sapphire laser pulses

H. Nakano, T. Nishikawa, H. Ahn, and N. Uesugi

Appl. Phys. Lett. 69, 2992 (1996); http://dx.doi.org/10.1063/1.117754 (3 pages) | Cited 28 times

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The temporal and spectral evolution of soft x‐ray pulses (40–100 Å) emitted from Al plasma produced by a pair of femtosecond Ti:sapphire laser pulses at normal incidence was studied. Both the soft x‐ray emission and the pulse duration increased with increase in the scale length of the preformed plasma. Prepulse enhanced soft x‐ray emission about 100 times with a pulse duration of 100–130 ps. A spectrally resolved time history revealed that the emission at shorter wavelengths started and decayed relatively more quickly, and emissions at longer wavelengths built up and decayed more slowly. © 1996 American Institute of Physics.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
78.70.En X-ray emission spectra and fluorescence

Hypercooling of completely miscible alloys

G. Wilde, G. P. Görler, and R. Willnecker

Appl. Phys. Lett. 69, 2995 (1996); http://dx.doi.org/10.1063/1.117755 (3 pages) | Cited 20 times

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Calorimetric measurements and undercooling investigations were performed on the high‐melting, completely miscible binary systems (Co, Ni, Fe)‐Pd. The alloys, characterized by phase diagrams with concavous liquidus and solidus lines, exhibit heat‐of‐fusion values considerably lower than calculated assuming ideal solution behavior. As a consequence, these metallic systems offer the possibility to achieve the hypercooling regime at a reduced extent of undercooling. Investigations on the undercoolability of the liquid alloys indicate the surmounting of the calculated hypercooling limit. Time‐resolved radiation thermometry experimentally proved the appearance of complete isenthalpic solidification. Metallographic investigations of samples solidified from different levels of undercooling revealed the corresponding stages of microstructural evolution. © 1996 American Institute of Physics.
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64.70.D- Solid-liquid transitions
81.30.Fb Solidification
65.20.-w Thermal properties of liquids
65.40.gd Entropy
05.70.-a Thermodynamics

Stable Ti‐based quasicrystal offers prospect for improved hydrogen storage

R. M. Stroud, A. M. Viano, P. C. Gibbons, K. F. Kelton, and S. T. Misture

Appl. Phys. Lett. 69, 2998 (1996); http://dx.doi.org/10.1063/1.117756 (3 pages) | Cited 41 times

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The desorption of hydrogen from a novel material, a Ti45Zr38Ni17‐H quasicrystal, was observed using high‐temperature powder x‐ray diffraction, demonstrating the potential utility of Ti‐based quasicrystals in place of crystalline or amorphous hydrides for hydrogen storage applications. The maximum observed change in hydrogen concentration was from 61 at. %, corresponding to a hydrogen‐to‐metal ratio (H/M) of 1.54, at 91 °C to less than 2.5 at. % (H/M=0.025) at 620 °C. The onset temperature of desorption is below 350 °C. Surface oxidation was found to promote the formation of crystalline hydride phases. Highly oxidized samples transformed to a mixture of the C14 Laves and C15 Laves crystalline hydrides, and the Ti2Ni phase. When the oxidation was less severe, a reversible transformation between the quasicrystal and crystalline hydride phases was clearly observed, demonstrating the stability of the Ti45Zr38Ni17 quasicrystal at very low hydrogen concentrations, and temperatures as high as 661 °C. This is the first evidence for a stable Ti‐based quasicrystal and for reversible hydrogen storage in a quasicrystalline phase. © 1996 American Institute of Physics.
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61.44.Br Quasicrystals
84.60.Ve Energy storage systems, including capacitor banks
61.05.cp X-ray diffraction

Color changes in thin porous silicon films caused by vapor exposure

Robert B. Bjorklund, Shahin Zangooie, and Hans Arwin

Appl. Phys. Lett. 69, 3001 (1996); http://dx.doi.org/10.1063/1.116819 (3 pages) | Cited 16 times

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Thin films of porous silicon formed by electrochemically etching silicon wafers changed color when exposed to an ambient atmosphere saturated in various organic solvent vapors. The degree of the color change was related to the refractive indices of the solvents. Analysis of the data using a four‐layer optical model indicated that the film refractive index increased up to 15% when solvent molecules replaced air in the pores. Solvent condensing from the saturated atmosphere filled up to 45% of the total void volume. Thermally oxidizing the films to make them hydrophilic resulted in surfaces which changed color upon exposure to water. © 1996 American Institute of Physics.
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78.55.Mb Porous materials
78.66.Db Elemental semiconductors and insulators
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

High efficiency in dry etching of Si for wavelengths around 120 nm

U. Streller, A. Krabbe, and N. Schwentner

Appl. Phys. Lett. 69, 3004 (1996); http://dx.doi.org/10.1063/1.116820 (3 pages) | Cited 4 times

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Microstructuring of Si with XeF2 can be optimized by increasing the contrast in choosing a wavelength with minimal nonselective etching. The efficiency of selective etching with optimal quality can be increased by factors of 100 and 500 by using wavelengths around 120 and 110 nm, respectively, in comparison to longer wavelengths around 200 nm. The high efficiency of typically 10 removed atoms per photon, the availability of optical materials for imaging and the potentially high spatial resolution at 120 nm compared to the conventional excimer laser and I‐line wavelengths present a perspective for generating line densities required in the Gbit range. © 1996 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
81.05.Cy Elemental semiconductors
85.40.Hp Lithography, masks and pattern transfer

The mechanism of texture formation during film growth: The roles of preferential sputtering and shadowing

Feng Ying, Richard W. Smith, and David J. Srolovitz

Appl. Phys. Lett. 69, 3007 (1996); http://dx.doi.org/10.1063/1.116821 (3 pages) | Cited 26 times

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Nonequilibrium molecular dynamics simulations have been employed to develop a mechanistic model for the development of an out‐of‐plane (fiber) texture in polycrystalline thin films. The depositing atoms preferentially sputter film atoms from grains with high surface energies. As the film grows, an atomic shadowing mechanism leads to the lateral growth of the grains with a height advantage—eventually leading to the occlusion of randomly oriented grains. © 1996 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Heteroepitaxy of CuInS2 on Si(111)

R. Hunger, R. Scheer, K. Diesner, D. Su, and H. J. Lewerenz

Appl. Phys. Lett. 69, 3010 (1996); http://dx.doi.org/10.1063/1.116822 (3 pages) | Cited 22 times

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Epitaxial layers of CuInS2 are grown on chemically hydrogen terminated Si(111) surfaces with 4° miscut by molecular beam epitaxy. The morphological and structural properties are determined by scanning electron microscopy, transmission electron microscopy, x‐ray diffraction, and texture analysis. The data show growth in the 〈112〉 direction and substantial twinning of the 75‐nm‐thick films. High‐resolution cross‐sectional micrographs of the interface indicate semicoherent epitaxial growth via an interfacial indium‐rich secondary phase. The pronounced faceting of the film surface is discussed in relation to twin lamellae. © 1996 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.Ct Interface structure and roughness
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Laser direct writing of oxide structures on hydrogen‐passivated silicon surfaces

M. Müllenborn, K. Birkelund, F. Grey, and S. Madsen

Appl. Phys. Lett. 69, 3013 (1996); http://dx.doi.org/10.1063/1.116823 (3 pages) | Cited 18 times

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A focused laser beam has been used to induce oxidation of hydrogen‐passivated silicon. The scanning laser beam removes the hydrogen passivation locally from the silicon surface, which immediately oxidizes in air. The process has been studied as a function of power density and excitation wavelength on amorphous and crystalline silicon surfaces in order to determine the depassivation mechanism. The minimum linewidth achieved is about 450 nm using writing speeds of up to 100 mm/s. The process is fully compatible with local oxidation of silicon by scanning probe lithography. Wafer‐scale patterns can be generated by laser direct oxidation and complemented with nanometer resolution by scanning probe techniques. The combined micro‐ and nanoscale pattern can be transferred to the silicon in a single etching step by either wet or dry etching techniques. © 1996 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
79.20.La Photon- and electron-stimulated desorption
81.65.Mq Oxidation
42.62.-b Laser applications

Room‐temperature repositioning of individual C60 molecules at Cu steps: Operation of a molecular counting device

M. T. Cuberes, R. R. Schlittler, and J. K. Gimzewski

Appl. Phys. Lett. 69, 3016 (1996); http://dx.doi.org/10.1063/1.116824 (3 pages) | Cited 87 times

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C60 molecules absorbed on a monoatomic Cu step have been reversibly repositioned at room temperature with the tip of a scanning tunneling microscope by performing controlled displacements along the step direction. We demonstrate the feasibility of building an abacus on the nanometer scale using single molecules as ‘‘counters,’’ Cu monoatomic steps as ‘‘rods’’ that constrain the molecular motion to one dimension, and the scanning tunneling microscope as an ‘‘actuator’’ for counting operations. © 1996 American Institute of Physics
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07.79.Cz Scanning tunneling microscopes
61.46.-w Structure of nanoscale materials
85.65.+h Molecular electronic devices

Structural characterization of Zn‐diffused InP layers by x‐ray diffraction and standing‐waves method

C. Bocchi, P. Franzosi, A. V. Maslov, E. Kh. Mukhamedzhanov, R. Audino, and N. Gambacorti

Appl. Phys. Lett. 69, 3019 (1996); http://dx.doi.org/10.1063/1.116825 (3 pages) | Cited 1 time

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Zn‐diffused InP layers have been prepared in a sealed quartz ampoule at 500 °C using a Zn3P2 source. The diffusion time ranged from 7 up to 90 min. As substrates, nearly dislocation‐free S‐doped InP crystals have been used. The lattice strain produced by diffusion has been carefully investigated by x‐ray double crystal diffraction and the standing‐waves method recording photoelectrons. The results show that the diffused layers exhibit a lattice contraction probably related to the Zn atoms substituting In. The diffuse/virgin interface has been found to be very sharp and the secondary ion mass spectrometry measurement of the Zn concentration profile has been confirmed. Finally, the maximum strain seems not to depend on the diffusion time, whereas the thickness of the diffused layer increases by increasing the time as expected for a diffusion process. © 1996 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.05.C- X-ray diffraction and scattering
66.30.J- Diffusion of impurities

Conduction band offsets in ordered‐GaInP/GaAs heterostructures studied by ballistic‐electron‐emission microscopy

J. J. O’Shea, C. M. Reaves, S. P. DenBaars, M. A. Chin, and V. Narayanamurti

Appl. Phys. Lett. 69, 3022 (1996); http://dx.doi.org/10.1063/1.116826 (3 pages) | Cited 26 times

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Ordered‐GaInP/GaAs heterostructures have been studied using ballistic‐electron‐emission microscopy (BEEM). The GaInP/GaAs conduction band offset was found to decrease with increasing order. Samples were grown simultaneously on different misoriented substrates to vary the degree of order in the GaInP. Concurrent scanning tunneling microscopy and BEEM images show ridge structures in the topography and contrast in the BEEM current that may correspond to ordered domains in the GaInP. Room temperature conduction band offsets of 137 and 86 meV were measured using BEEM spectroscopy for GaInP with 2 K band gaps of 1.97 and 1.89 eV, respectively. © 1996 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
71.20.Nr Semiconductor compounds
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy

Characteristics of Si3N4/Si/n‐GaAs metal‐insulator‐semiconductor interfaces grown on GaAs(111)B substrate

Dae‐Gyu Park, Deda M. Diatezua, Zhi Chen, S. Noor Mohammad, and Hadis Morkoç

Appl. Phys. Lett. 69, 3025 (1996); http://dx.doi.org/10.1063/1.116827 (3 pages) | Cited 5 times

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Interfacial properties of Al/Si3N4/Si/n‐GaAs metal‐insulator‐semiconductor (MIS) capacitors grown on GaAs(111)B prepared with a combination of in situ molecular beam epitaxy and chemical vapor deposition techniques are presented. The density of the surface states in the high 1010 eV−1 cm−2 near the GaAs midgap for the GaAs grown at 575 and 625 °C was obtained. The MIS structure with GaAs homoepitaxial layer grown at 625 °C, showing smoother surface morphology than the surface grown at 575 °C, exhibited small hysteresis which was as small as 30 mV under a field excursion of 1.5 MV/cm. The presence of a 1 MHz frequency response at 77 K requires that the traps be within 60 meV of the conduction band edge of GaAs and confirms the unpinned GaAs surface Fermi energy within GaAs band gap. © 1996 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.20.At Surface states, band structure, electron density of states
68.35.Ct Interface structure and roughness
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