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17 Oct 1994

Volume 65, Issue 16, pp. 1983-2110

Page 1 of 2 Pages Next Page | Jump to Page

Stochastic resonance in a semiconductor distributed feedback laser

J. M. Iannelli, A. Yariv, T. R. Chen, and Y. H. Zhuang

Appl. Phys. Lett. 65, 1983 (1994); http://dx.doi.org/10.1063/1.112838 (3 pages) | Cited 14 times

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The observation of stochastic resonance in a semiconductor distributed feedback laser is reported. Bistable modal and intensity operation is obtained using the degenerate modes of the grating. Through an observation of longitudinal‐mode switching under current modulation, an enhancement in the signal‐to‐noise ratio of the laser’s output wavelength switching of 22 dB is measured. © 1994 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Mi Dynamical laser instabilities; noisy laser behavior
42.65.Pc Optical bistability, multistability, and switching, including local field effects

Platinumsilicide Schottky barrier infrared detectors with a grating: Dependence of the optical response on wavelength and polarization

K. Kapser, P. P. Deimel, W. Platz, and U. Prechtel

Appl. Phys. Lett. 65, 1986 (1994); http://dx.doi.org/10.1063/1.113042 (3 pages) | Cited 2 times

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Platinumsilicide Schottky diodes on p‐Si substrates structured with a dry‐etched lamellar grating were fabricated. The grating periods Λ were 3, 4, and 5 μm, and the grating amplitude h ranged from 300 to 1100 nm. Measurements of the optical response Y for TE and TM polarized light were made. A strong dependence of the detector sensitivity on the polarization of the radiation was observed. Enchancement of the responsivity up to 70% was found compared to an unstructured reference sample. Calculations based on an optical model which takes into account the change in absorption due to the grating were made. The results show good agreement with the experimental data. © 1994 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
85.30.Hi Surface barrier, boundary, and point contact devices

Acoustic and optical properties of thallium ion‐exchanged KTiOPO4

David K. T. Chu

Appl. Phys. Lett. 65, 1989 (1994); http://dx.doi.org/10.1063/1.112839 (3 pages)

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Both acoustic and optical properties of thallium ion‐exchanged KTiOPO4 (Tl:KTP) plates were examined. Surface acoustic wave (SAW) velocity of the thallium‐exchanged z‐cut KTP possesses a reduction of 13% from the unchanged KTP. Temperature stability of SAW resonance (1/f0 df/dT) changed from ≊−81 ppm of an untreated z‐cut KTP substrate to ≊−121 ppm of a z‐cut Tl:KTP substrate. Large optical refractive indices changes at the Tl ion‐exchanged surface were observed [Δneff(TE)≊0.3, Δneff(TM)≊0.22]. Tl ion concentration profile from the crystal surface into substrate was also studied using electron beam microscopy and the optical index m‐line measurement. Tl‐exchanged KTP, therefore, possesses both acoustic and optical waveguiding properties. © 1994 American Institute of Physics.
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62.65.+k Acoustical properties of solids
43.35.Pt Surface waves in solids and liquids
61.72.up Other materials
42.79.Gn Optical waveguides and couplers

High power diode‐pumped Nd:YAG regenerative amplifier for picosecond pulses

D. R. Walker, C. J. Flood, H. M. van Driel, U. J. Greiner, and H. H. Klingenberg

Appl. Phys. Lett. 65, 1992 (1994); http://dx.doi.org/10.1063/1.112840 (3 pages) | Cited 7 times

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We demonstrate regenerative amplification of 25‐ps full width at half‐maximum TEM00 pulses to ≳1 mJ at a 2‐kHz repetition rate in a diode‐pumped Nd:YAG system. The single pulse energy gain is 74 dB and operation at 5 kHz has delivered ≳3.5 W of average power at λ=1.064 μm. Gain narrowing and self‐phase modulation cause significant spectral and temporal broadening, from 70 GHz and 12 ps to ∼100 GHz and 25 ps, respectively, for the shortest amplified pulses. © 1994 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes

Epitaxial growth of optical Ba2NaNb5O15 waveguide film by pulsed laser deposition

J. M. Liu, F. Zhang, Z. G. Liu, S. N. Zhu, L. J. Shi, Z. C. Wu, and N. B. Ming

Appl. Phys. Lett. 65, 1995 (1994); http://dx.doi.org/10.1063/1.112841 (3 pages) | Cited 14 times

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The waveguiding Ba2NaNb5O15 films have been prepared on KTiOPO4 substrates by pulsed laser deposition technique. Characterizations of the as-grown films by the x-ray θ–2θ scan and β scan and the scanning electron microscopy revealed that epitaxial (110)-oriented Ba2NaNb5O15 films with small surface roughness were achieved on (100)-oriented KTiOPO4 plates. The x-ray photoelectron spectrometer was employed to probe the chemical constitution of the as-grown films. Favorable optical waveguiding properties were demonstrated by m-line measurement and evaluation of propagation loss on the order of 1.0 dB/cm of TM and TE multimodes. © 1994 American Institute of Physics.
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81.15.Fg Pulsed laser ablation deposition
68.55.-a Thin film structure and morphology
78.66.Nk Insulators

Electrochromism in tungsten oxyfluoride films made by chemically enhanced dc sputtering

A. Azens, B. Stjerna, C. G. Granqvist, J. Gabrusenoks, and A. Lusis

Appl. Phys. Lett. 65, 1998 (1994); http://dx.doi.org/10.1063/1.112842 (3 pages) | Cited 9 times

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Tungsten oxyfluoride films were prepared by reactive dc sputtering in plasmas containing O2+CF4.. The deposition rate was large, particularly when chemical sputtering was promoted by heating the target. The films could show large charge insertion/extraction and high coloration efficiency. © 1994 American Institute of Physics.
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81.15.Cd Deposition by sputtering
78.66.Nk Insulators
78.20.Jq Electro-optical effects

‘‘Plastic’’ infrared polarizers from uniaxially oriented polyaniline blends

Y. Cao, N. Colaneri, A. J. Heeger, and Paul Smith

Appl. Phys. Lett. 65, 2001 (1994); http://dx.doi.org/10.1063/1.112843 (3 pages) | Cited 17 times

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We describe the preparation, characterization, and use of ‘‘plastic’’ infrared polarizers that consist of electrically conductive polyaniline blends with common bulk polymers such as poly(acrylonitrile), polyethylene, and poly(vinylalcohol). It is shown that uniaxially oriented blends of protonated polyaniline in, for example, poly(acrylonitrile) display a polarizing efficiency over the range from 400 to 4000 cm−1 that matches or surpasses that of commercial wire grid polarizers. © 1994 American Institute of Physics.
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42.79.Ci Filters, zone plates, and polarizers
78.66.Qn Polymers; organic compounds
78.30.Jw Organic compounds, polymers

Spatial profiling of ion and neutral excitation in noble gas electron cyclotron resonance plasmas

R. L. Rhoades and S. M. Gorbatkin

Appl. Phys. Lett. 65, 2004 (1994); http://dx.doi.org/10.1063/1.112844 (3 pages) | Cited 6 times

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Optical emission from neutrals and ions of several noble gases has been profiled in an electron cyclotron resonance plasma system. In argon plasmas with a net microwave power of 750 W, the neutral (696.5‐nm) and ion (488‐nm) emission profiles are slightly center peaked at 0.32 mTorr and gradually shift to a hollow appearance at 2.5 mTorr. Neon profiles show a similar trend from 2.5 to 10.0 mTorr. For the noble gases, transition pressure scales with the ionization potential of the gas, which is consistent with neutral depletion. Studies of noble gas mixtures, however, indicate that neutral depletion is not always dominant in the formation of hollow profiles. For Kr/Ar, Ar/Ne, and Ne/He plasmas, the majority gas tends to set the overall shape of the profile at any given pressure. For the conditions of the current system, plasma density appears to be more dominant than electron temperature in the formation of hollow profiles. The general method described is also a straightforward, inexpensive technique for measuring the spatial distribution of power deposited in plasmas, particularly where absolute scale can be calibrated by some other means. © 1994 American Institute of Physics.
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52.80.Pi High-frequency and RF discharges
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Jm Ionization of plasmas

Diffusion in nanolayers as measured by atom probing

Christian Keilonat, Eric Camus, Nelja Wanderka, and Heinrich Wollenberger

Appl. Phys. Lett. 65, 2007 (1994); http://dx.doi.org/10.1063/1.112845 (2 pages) | Cited 5 times

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Diffusion measurements by atom probing of Cu/Ni nanolayers are reported. Using the Matano analysis, we derive directly from the experimental data the concentration dependent interdiffusion coefficient in a temperature range from 653 to 703 K. © 1994 American Institute of Physics.  
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68.35.Fx Diffusion; interface formation
68.55.Nq Composition and phase identification
79.70.+q Field emission, ionization, evaporation, and desorption
68.37.Vj Field emission and field-ion microscopy

Activation energy for C94 and C54 TiSi2 formation measured during rapid thermal annealing

E. G. Colgan, L. A. Clevenger, and C. Cabral

Appl. Phys. Lett. 65, 2009 (1994); http://dx.doi.org/10.1063/1.112846 (3 pages) | Cited 19 times

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The activation energies Ea for C49 and C54 TiSi2 formation were determined using in situ resistance measurements during rapid thermal annealing. Ti films were evaporated on undoped polycrystalline Si (poly‐Si) and single‐crystal Si on sapphire (SOS) substrates. The resistance was monitored for heating rates from 1 to 95 °C/s up to 1000 °C. The Ea’s determined from Kissinger plots were 1.86±0.23 and 1.65±0.31 eV for C49 TiSi2 formation and 3.30±0.16 and 3.67±0.13 eV for C54 TiSi2 formation for Ti/poly‐Si and Ti/SOS samples, respectively. These are the first reported measurements of Ea’s for C49 and C54 TiSi2 formation at such high heating rates. The formation sequence remained the same for the range of heating rates examined. © 1994 American Institute of Physics.  
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68.55.-a Thin film structure and morphology
68.35.Md Surface thermodynamics, surface energies

In‐plane aligned CeO2 films grown on amorphous SiO2 substrates by ion‐beam assisted pulsed laser deposition

Shen Zhu, Douglas H. Lowndes, J. D. Budai, and D. P. Norton

Appl. Phys. Lett. 65, 2012 (1994); http://dx.doi.org/10.1063/1.112847 (3 pages) | Cited 23 times

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Both (001)‐ and (111)‐oriented CeO2 thin films have been grown on amorphous fused silica (SiO2) substrates by ion‐beam assisted pulsed laser ablation of a polycrystalline CeO2 target. Using 200 eV Ar+ ions incident at 55° to the substrate normal, the preferred orientation for CeO2 film growth is (001) at room temperature, but changes to (111) for temperatures ≥300 °C. Furthermore, the ion‐beam assisted CeO2 films exhibit strong in‐plane crystallographic alignment. In contrast, CeO2 films grown without ion‐beam assistance exhibit a mixture of polycrystalline orientations with the relative amounts depending on growth temperature. Under optimum conditions, off‐normal‐incidence Ar+ ions produce a (111)‐oriented crystalline CeO2 film that is aligned with respect to a single in‐plane axis, on an amorphous substrate. © 1994 American Institute of Physics.
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81.15.Fg Pulsed laser ablation deposition
81.15.Kk Vapor phase epitaxy; growth from vapor phase
77.55.-g Dielectric thin films

Laser‐induced phase transformation from amorphous to perovskite in PbZr0.44Ti0.56O3 films with the substrate at room temperature

X. M. Lu, J. S. Zhu, X. F. Huang, C. Y. Lin, and Y. N. Wang

Appl. Phys. Lett. 65, 2015 (1994); http://dx.doi.org/10.1063/1.112805 (3 pages) | Cited 12 times

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Radio‐frequency‐sputtered amorphous as‐grown PbZr0.44Ti0.56O3 (PZT) thin films were prepared on glass substrates from a PZT ceramic target with excess PbO. They were subsequently treated with a laser‐induced phase transformation technique to achieve a pure perovskite structure. The optimal conditions for the process were determined. During the whole fabrication process, the substrate was kept at room temperature. This technique was also compared with traditional oven and rapid thermal processing after‐deposition treatments. © 1994 American Institute of Physics.
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81.15.Cd Deposition by sputtering
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Growth of epitaxial strontium barium niobate thin films by pulsed laser deposition

S. Schwyn Thöny, K. E. Youden, J. S. Harris, and L. Hesselink

Appl. Phys. Lett. 65, 2018 (1994); http://dx.doi.org/10.1063/1.112780 (3 pages) | Cited 47 times

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We report the growth of epitaxial SrxBa1−xNb2O6 (SBN) thin films by pulsed laser deposition. The films were grown on (100) MgO substrates with thicknesses in the range 200–400 nm. Rutherford backscattering analysis showed that the films have stoichiometric composition identical to the target material. X‐ray diffraction 2θ scans indicate single crystalline layers with the (001) orientation perpendicular to the substrate plane. Phi scans on the (221) plane, however, reveal that the films have two in‐plane orientations. The unit cell of SBN is rotated in the plane of the film by ±18.4° with respect to the MgO substrate unit cell. This rotation is explained using a model which takes into account both the lattice match and the electrostatic energy within the heteroepitaxial interface. © 1994 American Institute of Physics.
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81.15.Fg Pulsed laser ablation deposition
68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification

Low pressure microwave electron cyclotron resonance plasma deposition of amorphous Ta2O5 films

D. Laviale, J. C. Oberlin, and R. A. B. Devine

Appl. Phys. Lett. 65, 2021 (1994); http://dx.doi.org/10.1063/1.112781 (3 pages) | Cited 30 times

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Deposition of Ta2O5 from Ta(OC2H5)5 and O2 has been studied using a distributed electron cyclotron resonance plasma. Carbon contamination levels as low as 1.5% have been obtained when the Ta(OC2H5)5 vapor is introduced ‘‘downstream’’ away from the plasma volume. Electrical measurements (current density/voltage, capacitance/voltage) suggest the films have dielectric constants ∼22 and leakage currents ∼10−10 A cm−2 for 2 V operation (50 nm thick, 10 nm a‐SiO2 equivalent). These values are obtained without the necessity for high temperature annealing and recrystallization. The conduction mechanism is attributed to the Poole–Frenkel effect. © 1994 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.22.Ch Permittivity (dielectric function)
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

High quality self‐nucleated AlxGa1−x N layers on (00.1) sapphire by low‐pressure metalorganic chemical vapor deposition

D. K. Wickenden, C. B. Bargeron, W. A. Bryden, J. Miragliotta, and T. J. Kistenmacher

Appl. Phys. Lett. 65, 2024 (1994); http://dx.doi.org/10.1063/1.112782 (3 pages) | Cited 57 times

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High quality AlxGa1−xN alloy films with x<0.4 have been prepared on self‐nucleated (00.1) sapphire substrates by low‐pressure metalorganic chemical vapor deposition. It has been shown that the lattice constant of the films varies linearly with alloy composition x (Vegard’s law is obeyed) and that homogeneous and inhomogeneous strain and alloy clustering are minimized in these self‐nucleated AlxGa1−xN films. Consistent with their reduced strain and chemical uniformity, the derived optical band gaps of these AlxGa1−xN films also show a linear dependence on alloy composition x, yielding a bowing parameter b≊0 eV. © 1994 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology
78.66.Fd III-V semiconductors

Effect of interfaces on the electrical behavior of (Pb0.72La0.28)TiO3 thin films

J. J. Lee, P. Alluri, and S. K. Dey

Appl. Phys. Lett. 65, 2027 (1994); http://dx.doi.org/10.1063/1.112783 (3 pages) | Cited 15 times

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Paraelectric (Pb0.72La0.28)TiO3 or PLT(28) thin films were deposited on platinum coated Si substrates by the sol‐gel technique. Two distinct groups of top metals, namely MT (Ni, Cr, and Ti, i.e., transition metals) and MN (Pt, Au, and Ag, i.e., noble metals) formed Ohmic and Schottky contacts, respectively. A Schottky barrier height of 1.83 eV at the Pt‐PLT interface was determined. The conventional Schottky emission and Fowler–Nordheim tunneling equations were modified to account for the voltage dependence of the interfacial permittivity. It was found that Schottky emission, thermionic tunneling, and Fowler–Nordheim tunneling mechanisms were predominant in the voltage ranges of 2<V<7, 7<V<16, and V≳16, respectively. © 1994 American Institute of Physics.
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73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions
77.22.-d Dielectric properties of solids and liquids

Carrier deep‐trapping mobility‐lifetime products in poly(p‐phenylene vinylene)

H. Antoniadis, M. A. Abkowitz, and B. R. Hsieh

Appl. Phys. Lett. 65, 2030 (1994); http://dx.doi.org/10.1063/1.112784 (3 pages) | Cited 102 times

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In order to estimate the deep‐trapping mobility‐lifetime (μτ) product for holes and electrons in poly(p‐phenylene vinylene) (PPV), trap‐free space‐charge‐limited current, and time‐of‐flight measurements were performed on bilayer devices comprising of a PPV layer and a trap‐free molecularly doped polymer layer. μτ products of about 10−9 and 10−12 cm2/V were found for holes and electrons respectively, corresponding to an average range of 1 μm for holes and 10 Å for electrons under an electric field of 105 V/cm. The low μτ value for electrons is attributed to severe deep trapping of electrons in PPV, which effectively reduces their range. Implications on the efficiency of electroluminescence devices are discussed. © 1994 American Institute of Physics.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.80.Le Polymers; organic compounds (including organic semiconductors)
78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds

Carrier‐induced strain effect in Si and GaAs nanocrystals

X. S. Zhao, Y. R. Ge, J. Schroeder, and P. D. Persans

Appl. Phys. Lett. 65, 2033 (1994); http://dx.doi.org/10.1063/1.112999 (3 pages) | Cited 13 times

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New experimental results on Raman scattering from porous silicon and silicon and gallium arsenide nanocrystals are reported. In all of these systems, almost all vibrational modes become Raman active and are remarkably soft. A carrier‐induced strain model is proposed to explain the optical properties of these nanocrystal systems. According to this carrier‐induced strain model, the selection rule of crystal momentum conservation for Raman scattering is greatly relaxed in Si and GaAs nanocrystals due to the dilatation strain caused by coupling of excited free carriers with the particle lattice and the optical properties of such systems are dominated by multiphonon assisted free‐electron transition processes. © 1994 American Institute of Physics.
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78.30.Hv Other nonmetallic inorganics
63.20.-e Phonons in crystal lattices
78.55.Hx Other solid inorganic materials
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Synchrotron radiation photoelectron spectroscopy study for GaAs (001) surface prepared by deoxygenated and de‐ionized water treatment

Y. Hirota, T. Ogino, Y. Watanabe, and M. Oshima

Appl. Phys. Lett. 65, 2036 (1994); http://dx.doi.org/10.1063/1.112785 (3 pages) | Cited 4 times

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The thermal effects on an n‐type GaAs (001) surface prepared by deoxygenated and de‐ionized water (DODIW) treatment are investigated by synchrotron‐radiation photoelectron spectroscopy (SRPES) in the temperature range from room temperature (RT) to 500 °C. SRPES confirms there are no oxides. There is, however, excess elemental arsenic and/or hydrogenated arsenic on the surface before heating, which evaporates when heated in a high vacuum. SRPES also shows that the surface Fermi level lies almost 0.9 eV above the maximum of valence band before heating, and moves toward the midgap during heating. After cooling to RT, it returns to the near‐flat band position (1.0 eV). These experimental results suggest that DODIW‐treated GaAs (001) surface can attain a low‐density surface state. © 1994 American Institute of Physics.
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81.65.-b Surface treatments
73.20.At Surface states, band structure, electron density of states

Phonon‐assisted carrier capture into a quantum well in an electric field

L. Thibaudeau and B. Vinter

Appl. Phys. Lett. 65, 2039 (1994); http://dx.doi.org/10.1063/1.112786 (3 pages) | Cited 5 times

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We have theoretically investigated the capture of electrons into a quantum well by LO phonon scattering. The calculation was performed for a single, undoped GaAs/AlxGa1−xAs quantum well under applied electric bias. We have derived an expression for the time constant associated with the exchange of electrons between the fundamental ground state and the continuum states. The results are found to be in fairly good agreement with impedance spectroscopy measurements. © 1994 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Pz Photoconduction and photovoltaic effects

Dependence on the In concentration of the piezoelectric field in (111)B InGaAs/GaAs strained heterostructures

J. L. Sánchez‐Rojas, A. Sacedón, F. González‐Sanz, E. Calleja, and E. Muñoz

Appl. Phys. Lett. 65, 2042 (1994); http://dx.doi.org/10.1063/1.112787 (3 pages) | Cited 42 times

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A series of (111)B InxGa1−xAs/GaAs multiple quantum well p‐i‐n structures have been investigated via low temperature photocurrent and photoluminescence spectroscopies. The indium mole fraction was in the range of 0.07–0.23. Evolution of the experimental blueshifts of the transition energies, with the external bias, agreed very well with the theoretical calculations. This allowed us to obtain precise information about the piezoelectric constant, e14, for the various In compositions. For the range of x investigated, we have found e14(x) to be linear with x but significantly lower than predicted by a simple linear interpolation of the accepted values for GaAs and InAs. © 1994 American Institute of Physics.
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77.65.Bn Piezoelectric and electrostrictive constants
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects

Semiconductor characterization with the scanning surface harmonic microscope

J.‐P. Bourgoin, M. B. Johnson, and B. Michel

Appl. Phys. Lett. 65, 2045 (1994); http://dx.doi.org/10.1063/1.112788 (3 pages) | Cited 19 times

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The scanning surface harmonic microscope, in which a microwave signal is applied across a tip‐sample tunneling gap and higher harmonics are detected, is sensitive to the capacitance/voltage characteristics of semiconductor samples on a nanometer scale. We demonstrate its sensitivity to a wide range of dopant concentrations on Si, and its applications as a dopant profiler. Depletion regions are delineated with remarkable sensitivity, and variations in dopant concentration over a 35‐nm scale are discussed. Indications of a 5 nm resolution have been obtained. © 1994 American Institute of Physics.  
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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
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.S- Impurities in crystals

Normal incidence second‐harmonic generation in L‐valley AlSb/GaSb/Ga1−xAlxSb/AlSb stepped quantum wells

H. Xie, W. I. Wang, J. R. Meyer, and L. R. Ram‐Mohan

Appl. Phys. Lett. 65, 2048 (1994); http://dx.doi.org/10.1063/1.112789 (3 pages) | Cited 21 times

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A novel mechanism is proposed for surface‐emitting second‐harmonic generation at normal incidence using L‐valley intersubband transitions in AlSb/GaSb/Ga1−xAlxSb/AlSb stepped quantum wells. The calculations indicate that second‐harmonic susceptibilities of at least 9×10−8 m/V should be achievable under double resonance conditions, which is comparable to the best obtainable in GaAs/Ga1−xAlxAs systems for realistic propagation angles (e.g., 45°). Besides the advantage of normal‐incidence geometry, the large L‐valley conduction band offset between GaSb and AlSb enables doubling to frequencies spanning the entire midwave infrared spectral region. © 1994 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

InAs island‐induced‐strain driven adatom migration during GaAs overlayer growth

Qianghua Xie, P. Chen, and A. Madhukar

Appl. Phys. Lett. 65, 2051 (1994); http://dx.doi.org/10.1063/1.112790 (3 pages) | Cited 115 times

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The impact of the strain fields associated with partially strain relaxed InAs islands on GaAs (100) on the evolution of the growth front profile during subsequent GaAs capping layer growth as a function of the growth temperature is examined via placement of very thin AlGaAs marker layers. Transmission electron microscope studies reveal the presence of strain dominated atom migration away from the islands over dynamically evolving length scales of ∼100–400 Å at higher growth temperature whereas at lower growth temperature such an effect is minimal. Anisotropy in the length scale of impact between the [011] and [011] directions is observed. Estimates based upon a suitably adapted formulation of the classical theory of grain growth shows the mass transport to be dominantly strain rather than surface curvature driven. © 1994 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology

Growth and electrical transport properties of very high mobility two‐dimensional hole gases displaying persistent photoconductivity

M. Henini, P. J. Rodgers, P. A. Crump, B. L. Gallagher, and G. Hill

Appl. Phys. Lett. 65, 2054 (1994); http://dx.doi.org/10.1063/1.112791 (3 pages) | Cited 20 times

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We report on the growth by molecular beam epitaxy of modulation‐doped GaAs‐(Ga,Al)As heterostructures with low‐temperature hole mobility exceeding 1.2×106 cm2 V−1 s−1 with carrier concentrations as low as 0.8×1011 cm−2: The highest value observed at such low densities. We also report the first observation of persistent positive photoconductivity in a two‐dimensional hole gas. An analysis of the number density and temperature dependence of the mobility leads us to conclude that the mobility is limited by phonon scattering above ∼4 K and interface scattering at lower temperatures. © 1994 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Dn Low-field transport and mobility; piezoresistance
73.50.Pz Photoconduction and photovoltaic effects
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