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23 Mar 1992

Volume 60, Issue 12, pp. 1413-1519

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High power 1.017‐μm strained‐layer quantum well lasers grown by metalorganic chemical‐vapor deposition

Michio Ohkubo, Tetsuro Ijichi, Akira Iketani, and Toshio Kikuta

Appl. Phys. Lett. 60, 1413 (1992); http://dx.doi.org/10.1063/1.107306 (2 pages) | Cited 4 times

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We have fabricated InGaAs/GaAs/InGaP strained‐layer single quantum well (SLSQW) lasers emitting at 1.017 μm, which are suitable pumping sources for Pr3+‐doped fluoride 1.3‐μm fiber amplifiers, grown by metalorganic chemical‐vapor deposition (MOCVD). A very low threshold current density of 80 A/cm2 was obtained for the broad‐area lasers. This value is comparable to that of 0.98‐μm SLSQW lasers. Continuous wave light output power of over 100 mW was achieved on the 2‐μm‐wide ridge waveguide lasers.  
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42.55.Px Semiconductor lasers; laser diodes
42.60.-v Laser optical systems: design and operation
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Novel organic molecular second harmonic generation crystal: 3‐methoxy‐4‐hydroxy‐benzaldehyde

X. T. Tao, D. R. Yuan, N. Zhang, M. H. Jiang, and Z. S. Shao

Appl. Phys. Lett. 60, 1415 (1992); http://dx.doi.org/10.1063/1.107307 (3 pages) | Cited 21 times

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In considering the trade‐off between second‐order nonlinearity and transparency, a new organic molecular crystal 3‐methoxy‐4‐hydroxy‐benzaldehyde (MHBA) has been grown from solution by the temperature lowering method for the first time. MHBA belongs to the monoclinic system, and its space group is P21. The unit cell dimensions are: a=14.057, b=7.875, c=15.037 Å with β=115.45°. The powder second harmonic generation of MHBA is 30 times higher than that of urea and the cutoff wavelength is 370 nm.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
81.10.Dn Growth from solutions

Role of electrorefraction in quantum‐well Fabry–Perot modulators

G. Livescu, G. D. Boyd, R. A. Morgan, L. M. F. Chirovsky, A. M. Fox, R. E. Leibenguth, M. T. Asom, and M. W. Focht

Appl. Phys. Lett. 60, 1418 (1992); http://dx.doi.org/10.1063/1.107308 (3 pages) | Cited 8 times

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The effects of electrorefraction in quantum‐well Fabry–Perot (FP) modulators are discussed theoretically and illustrated experimentally. The large electrorefraction at the zero‐field heavy‐hole exciton is shown to produce strong modulation in FP devices operated at that wavelength. At longer operating wavelengths, the weakening electrorefraction plays a diminishing role. By taking into account the field dependent absorption α(λ,E) and dispersion n(λ,E) of the quantum‐well material, the measured reflectivity spectra are successfully modeled.  
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42.79.Hp Optical processors, correlators, and modulators
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
78.20.Jq Electro-optical effects

Temperature‐tuned noncritically phase‐matched picosecond LiB3O5 optical parameter oscillator

M. Ebrahimzadeh, G. J. Hall, and A. I. Ferguson

Appl. Phys. Lett. 60, 1421 (1992); http://dx.doi.org/10.1063/1.107309 (3 pages) | Cited 8 times

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Efficient picosecond optical parametric oscillation in LiB3O5 is demonstrated using ∼55 ps pump pulses at 523.5 nm, obtained from a frequency‐doubled, mode‐locked, Q‐switched, diode‐laser‐pumped Nd:YLF laser. By exploiting temperature tuning under noncritical type I phase matching, continuously tunable radiation over the range 0.909–1.235 μm has been generated at external power conversion efficiencies approaching 50%. The oscillator has a pump power threshold of 4.5 mW, corresponding to a Q‐switched pulse energy of 9 μJ, and can provide a total average output power of 8 mW at 500 Hz, in pulses of ∼33 ps duration. At five times above threshold, the internal pump depletion of the oscillator was 54%.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Nv Optical frequency converters

Diode array‐pumped Er, Yb: Phosphate glass laser

J. Andrew Hutchinson and Toomas H. Allik

Appl. Phys. Lett. 60, 1424 (1992); http://dx.doi.org/10.1063/1.107310 (3 pages) | Cited 50 times

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A diode‐array side‐pumped Er, Yb: phosphate glass laser has been constructed. Pumped with two 970 nm, InGaAs strained‐layer diode arrays, a long pulse slope efficiency of 14% was obtained, with thresholds of 60 mJ input, a maximum output pulse energy of 20 mJ, and with output wavelengths at 1545±12 nm. When Q‐switched, the laser generated 0.3 mJ, 50 ns FWHM pulses at an output wavelength of 1533±1 nm. Visible upconversion emission in the laser rod was observed.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Px Semiconductor lasers; laser diodes
42.60.-v Laser optical systems: design and operation

All‐optical switching in a nonlinear periodic‐waveguide structure

N. D. Sankey, D. F. Prelewitz, and T. G. Brown

Appl. Phys. Lett. 60, 1427 (1992); http://dx.doi.org/10.1063/1.107311 (3 pages) | Cited 79 times

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We report what we believe is the first observation of all‐optical switching in a nonlinear periodic‐waveguide structure. Measurements on the silicon‐on‐insulator waveguides were taken at 1.064 μm and at energies ranging from 1 to 18 μJ/pulse using a Nd:YAG pulsed laser. The measurements confirm theoretical predictions of bistability at low intensities with unstable dynamics at higher pulse energies.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Gn Optical waveguides and couplers

Pyrochlore to perovskite phase transformation in sol‐gel derived lead‐zirconate‐titanate thin films

Chi Kong Kwok and Seshu B. Desu

Appl. Phys. Lett. 60, 1430 (1992); http://dx.doi.org/10.1063/1.107312 (3 pages) | Cited 54 times

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Pyrochlore to perovskite phase transformation in sol‐gel derived lead‐zirconate‐titanate (PZT) films was studied by x‐ray diffraction and transmission‐electron microscopy (TEM). X‐ray diffraction studies of PZT films on sapphire substrates indicated that the pyrochlore to perovskite phase transformation was completed at 650 °C. In contrast, TEM investigations of free‐standing PZT films showed that the phase transformation was completed at much higher temperatures. This discrepancy in the behavior of free‐standing films versus films on substrate can be related to the size effect.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.30.-t Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
77.80.-e Ferroelectricity and antiferroelectricity

Amorphization of M‐Si (M=Ni, Co, Mo, Mn, and Cr) powders by ball milling using revolution‐step‐like‐decreasing mode

K. Omuro and H. Miura

Appl. Phys. Lett. 60, 1433 (1992); http://dx.doi.org/10.1063/1.107313 (3 pages) | Cited 8 times

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Amorphous alloy powders of the silicide type M‐Si (M=Ni, Co, Mo, Mn, and Cr) are produced from crystalline elemental powders by high‐energy ball milling using revolution‐step‐like‐decreasing (RSD) mode. In the ball milling using the RSD mode, after promoting true chemical alloying in milled powder samples under high‐vial rotation of the ball mill in the earlier stage, the medium‐ or low‐vial rotations in the successive milling stages lead to amorphization of powder products due to making recovery processes, like nucleation of more stable phases, less prevailing. Amorphicity of the RSD milled powder samples is examined by x‐ray diffraction and/or differential scanning calorimetry.  
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81.20.-n Methods of materials synthesis and materials processing
61.43.Fs Glasses
61.43.-j Disordered solids
61.44.Br Quasicrystals
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties

Observation of a super‐periodic feature on gold with a scanning tunneling microscope

M. J. Wilkins, M. C. Davies, D. E. Jackson, C. J. Roberts, S. J. B. Tendler, and P. M. Williams

Appl. Phys. Lett. 60, 1436 (1992); http://dx.doi.org/10.1063/1.107289 (2 pages) | Cited 3 times

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In this letter we present the first reported images of a super‐periodic hexagonal lattice observed on gold in air by scanning tunneling microscopy. The surface features presented extend over large areas (up to 1.0×105 nm2) with an average periodicity of 8 nm, and a corrugation of 1 nm. The impact of comparable results on highly oriented pyrolytic graphite suggests the need for some caution when using gold in biomolecular scanning tunneling microscopy studies.      
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68.35.B- Structure of clean surfaces (and surface reconstruction)
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
87.80.-y Biophysical techniques (research methods)

Wear‐induced phase transformation in yttria stabilized zirconia: X‐ray photoelectron spectroscopic studies

Dilip Chatterjee, Debasis Majumdar, Syamal Ghosh, and Thomas Blanton

Appl. Phys. Lett. 60, 1438 (1992); http://dx.doi.org/10.1063/1.107290 (3 pages) | Cited 2 times

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X‐ray photoelectron spectroscopy has been used to study near‐surface phase transformation in yttria stabilized zirconia subjected to sliding wear. Characteristic differences are observed in the valence bands of the tetragonal and the monoclinic phases of zirconia. These valence bands have been used as ‘‘fingerprints’’ to monitor phase transformation during wear under different loading conditions. Conventional and glancing angle x‐ray diffraction techniques were found inadequate to detect this phase transformation.
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81.40.Pq Friction, lubrication, and wear
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments
64.70.K- Solid-solid transitions

Strain tensor elements for misfit‐strained [hhk]‐oriented cubic crystals

E. A. Caridi and J. B. Stark

Appl. Phys. Lett. 60, 1441 (1992); http://dx.doi.org/10.1063/1.107264 (3 pages) | Cited 23 times

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We calculate the strain tensor components for (hhk)‐oriented cubic materials with misfit‐generated strain. We assume the strained layer to be free of crystalline defects, and derive the tensor elements via minimization of the crystal strain energy with the imposed constraint that the epitaxial film remains in registry with the substrate lattice. The strain components described, both in the crystalline basis and in the basis of the growing film, are written in terms of the lattice mismatch and the growth‐axis Miller indices. We show that the accommodation of misfit‐generated strain produces a tetragonal distortion for all (hhk)‐grown layers, and use the above results to interpret x‐ray diffraction data.
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68.55.-a Thin film structure and morphology
62.20.-x Mechanical properties of solids
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Electron cyclotron resonance plasma‐enhanced filament‐assisted diamond growth

W. Tsai, G. J. Reynolds, S. Hikido, and C. B. Cooper

Appl. Phys. Lett. 60, 1444 (1992); http://dx.doi.org/10.1063/1.107265 (3 pages) | Cited 4 times

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A novel technique was developed to grow high‐purity polycrystalline diamond films at 850 °C and 50 mTorr with 10% CH4, 2% O2, and balance H2 using a filament‐assisted chemical vapor deposition technique in combination with an electron cyclotron resonance (ECR) plasma. Using Raman spectroscopy and in situ plasma diagnostics, we have shown that the hydrogen plasma selectively etched nondiamond components during deposition. Experiments with ECR plasma and the filament‐assisted technique from 10−6 Torr to 50 mTorr and 500–1000 °C indicated that low‐energy electrons are a key factor in growth of diamond thin films.
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68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Distribution of radiation defects in submicron subsurface crystal layers

Victor A. Chaplanov and Aleksey A. Nefedov

Appl. Phys. Lett. 60, 1447 (1992); http://dx.doi.org/10.1063/1.107266 (3 pages) | Cited 1 time

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The degradation of the structure of a silicon surface irradiated with high‐energy (6 MeV) electrons has been studied by x‐ray asymptotic Bragg diffraction. The results of the investigation of the spatial distribution of radiation defects in subsurface layers with atomic scale resolution are presented. The thickness of the distorted layer on the Si‐crystal surface is close to 6 nm. The interplanar distance in this layer was decreased, which means that the main radiation defects in the subsurface region are vacancylike. Previous oxidation of silicon has prevented the distortion on the real Si‐surface. Interstitial atoms, which have been created under oxidation, have recombined with radiation defects. It has resulted in suppressing the subsurface distortions. The reasons for the observed effects are discussed.
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61.80.Fe Electron and positron radiation effects
81.65.-b Surface treatments
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Displacement threshold energy for type IIa diamond

J. Koike, D. M. Parkin, and T. E. Mitchell

Appl. Phys. Lett. 60, 1450 (1992); http://dx.doi.org/10.1063/1.107267 (3 pages) | Cited 61 times

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A type IIa natural diamond was irradiated at room temperature with energetic electrons. The threshold energy for displacement of atoms from their lattice sites was determined for three principal crystallographic directions by observing the formation of defect clusters during irradiation in a transmission electron microscope. The displacement‐threshold energies were found to be 37.5±1.2 eV for the electron incident in the [100] direction, 45.0±1.3 eV in the [111] direction, and 47.6±1.3 eV in the [110] direction.
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61.80.Fe Electron and positron radiation effects
61.72.Bb Theories and models of crystal defects

Raman study of low growth temperature GaAs

T. A. Gant, H. Shen, J. R. Flemish, L. Fotiadis, and M. Dutta

Appl. Phys. Lett. 60, 1453 (1992); http://dx.doi.org/10.1063/1.107268 (3 pages) | Cited 17 times

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A Raman study has been made of GaAs grown by MBE at low temperature, which is known to produce nonstoichiometric (As‐rich) material. The epilayer has a slightly larger lattice constant than the GaAs substrate, as measured by x‐ray diffraction. Raman measurements show that the LO phonon of LT‐GaAs is shifted down in frequency from that of bulk GaAs. The shift is related to the presence of AsGa antisite defects, which cause a reduction in the electric field associated with the LO phonon. After the sample was annealed, the epilayer had the same lattice constant as the substrate, and the LO phonon moved closer to that of bulk GaAs.
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68.55.-a Thin film structure and morphology
78.30.Fs III-V and II-VI semiconductors

Optical time‐of‐flight measurement of carrier transport in GaAs/AlxGa1−xAs and In0.53Ga0.47As/In0.52Al0.48As multiquantum wells

S. Gupta, L. Davis, and P. K. Bhattacharya

Appl. Phys. Lett. 60, 1456 (1992); http://dx.doi.org/10.1063/1.107269 (3 pages) | Cited 7 times

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An all‐optical time‐of‐flight technique is used for measuring perpendicular carrier transport in semiconductor heterostructures and multiquantum wells (MQWs). This technique is based on measuring a change in surface reflectance due to the absorption nonlinearities induced by the carriers, and has a temporal resolution of ∼1 ps. Typical results on a GaAs/AlxGa1−xAs MQW and an In0.53Ga0.47As/In0.52Al0.48As MQW are compared. The observed fast transport times can only be explained by a field‐dependent carrier emission out of the quantum well, after which transport through the continuum states can occur. Due to larger barriers in the In0.53Ga0.47As/In0.52Al0.48As system, this intrinsic limit to transport is much larger, and hence these devices are observed to be slower than their GaAs/AlxGa1−xAs counterparts.
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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
78.47.-p Spectroscopy of solid state dynamics

Vapor etching of GaAs and AlGaAs by CH3I

C. W. Krueger, C. A. Wang, and M. Flytzani‐Stephanopoulos

Appl. Phys. Lett. 60, 1459 (1992); http://dx.doi.org/10.1063/1.107270 (3 pages) | Cited 3 times

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With the objective of developing an improved process for in situ etching of GaAs‐based materials in organometallic vapor phase epitaxy reactors, GaAs wafers and AlxGa1−xAs epilayers have been etched with CH3I vapor in a horizontal reactor operated at atmospheric pressure with H2 or He carrier gas. For a H2 flow rate of 2.1 s lpm, etching temperatures from 400 to 625 °C, and CH3I mol fractions (yCH3I)from 0.0012 to 0.015, the measured GaAs etch rate r (in Å min−1) is given by r = k0 y0.83CH3I exp[ − 45(kcal mol−1)/RT] with k0=3.2×1016 Å min−1. The value of k0 depends on the type of carrier gas, flow rate, total pressure, and reactor geometry. The etch rate appears to be controlled mainly by the decomposition of CH3I to CH3 and I, for which the activation energy has been reported to be 43.5 kcal mol−1. The etch rate of AlxGa1−xAs epilayers with x up to 0.7, which was measured at 480 °C with yCH3I= 0.015, does not depend on Al content. The surface morphology of etched GaAs wafers improves with decreasing temperature. Specular surfaces are maintained at temperatures below 500 °C for etch depths up to 5000 Å.
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81.65.-b Surface treatments
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Temperature and intensity dependence of the saturated density of light‐induced defects in hydrogenated amorphous silicon

N. Hata, M. Isomura, and S. Wagner

Appl. Phys. Lett. 60, 1462 (1992); http://dx.doi.org/10.1063/1.107271 (3 pages) | Cited 14 times

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We compare experimental data for the saturated light‐induced defect density Nsat in hydrogenated amorphous silicon with results obtained by a quasi‐equilibrium model. If the model draws on a limited pool of defects the results agree with the experimental data, but if the model relies on the conversion of valence‐band‐tail states they do not. The model reproduces all three regimes of Nsat: a constant, maximum value of Nsat at high carrier generation rate G and low‐temperature T; the dependence of Nsat on both G and T at intermediate temperature; and independence of G coupled with dependence on T at high temperature.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.72.Bb Theories and models of crystal defects
71.23.-k Electronic structure of disordered solids
78.30.-j Infrared and Raman spectra
78.40.Fy Semiconductors

Density of states in the pseudo‐gap of amorphous silicon‐germanium alloys from electrical and optical measurements

T. Pisarkiewicz, A. Kolodziej, E. Schabowska‐Osiowska, T. Stapinski, A. Rodzik, and P. Rava

Appl. Phys. Lett. 60, 1465 (1992); http://dx.doi.org/10.1063/1.107272 (3 pages) | Cited 6 times

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Amorphous hydrogenated silicon‐germanium alloys a‐Si1−xGex:H in the form of thin films were prepared by rf sputtering and chemical vapor deposition methods with x varying from 0 to 0.63. Optical transmission, reflection, and photoconductivity measurements in the visible and near‐infrared regions of light enabled determination of the optical energy gap, band‐tail states distribution, and density of defect states near midgap. Dark conductivity and photoconductivity were measured in the temperature range of 300–500 K. Electronic band structure (density of states versus energy) for a‐Si0.74Ge0.26:H thin film was derived on the basis of optical measurements, dark conductivity, and photoconductivity.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
71.23.-k Electronic structure of disordered solids
78.66.-w Optical properties of specific thin films

Improvement in heteroepitaxial film quality by a novel substrate patterning geometry

R. Hull, J. C. Bean, G. S. Higashi, M. L. Green, L. Peticolas, D. Bahnck, and D. Brasen

Appl. Phys. Lett. 60, 1468 (1992); http://dx.doi.org/10.1063/1.107273 (3 pages) | Cited 19 times

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We describe a novel substrate patterning geometry which can reduce epilayer threading dislocation densities by up to two orders of magnitude in GexSi1−x/Si(100) (x∼0.15–0.20) het‐ eroepitaxial layers. The basic pattern consists of a two‐dimensional array of ∼2 μm diameter oxide pillars which are separated from each other by varying pitch dimensions, and which are staggered slightly from their neighbors with respect to the in‐plane 〈011〉 directions. This ensures that a misfit dislocation nucleating at any point within the epilayer must eventually propagate into one of the pillars, where the threading end will be terminated. Prospects for surface planarization and overgrowth of the pillars are discussed.
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68.55.-a Thin film structure and morphology

Transport asymmetry and photovoltaic response in (AlGa)As/AlAs/GaAs/(AlGa)As single‐barrier quantum‐well infrared detectors

H. Schneider, K. Kheng, M. Ramsteiner, J. D. Ralston, F. Fuchs, and P. Koidl

Appl. Phys. Lett. 60, 1471 (1992); http://dx.doi.org/10.1063/1.107274 (3 pages) | Cited 11 times

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We have studied the wavelength and electric‐field characteristics of intersubband photodetectors where a thin AlAs tunnel barrier was introduced between one side of the GaAs quantum well and thicker layers of (AlGa)As. The photoresponse of these structures has an extremely broad (3–11 μm) spectral range and there is a preferential escape direction of the photoexcited carriers towards one direction of the quantum wells giving rise to photovoltaic detector behavior. We found evidence that this transport asymmetry is not only caused by the asymmetric potential distribution, but that interface scattering processes are involved. These scattering processes act differently on the photocurrent and the dark current, which is useful for further optimization of quantum‐well infrared detectors.
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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
85.60.Gz Photodetectors (including infrared and CCD detectors)

Hole space‐charge buildup and evidence for sequential tunneling in p‐type double‐barrier resonant tunneling devices

R. K. Hayden, L. Eaves, M. Henini, D. K. Maude, J. C. Portal, and G. Hill

Appl. Phys. Lett. 60, 1474 (1992); http://dx.doi.org/10.1063/1.107275 (3 pages) | Cited 16 times

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Magnetoquantum oscillations in the tunnel current of a p‐type double‐barrier AlAs/GaAs/AlAs device are used to measure the buildup of hole space charge in the quantum well over a wide range of bias. These measurements demonstrate sequential tunneling of holes. The effective mass for hole tunneling is estimated.
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73.40.Gk Tunneling
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

Intervalley scattering in GaAs and InP probed by pulsed far‐infrared transmission spectroscopy

Peter N. Saeta, John F. Federici, Benjamin I. Greene, and Douglas R. Dykaar

Appl. Phys. Lett. 60, 1477 (1992); http://dx.doi.org/10.1063/1.107276 (3 pages) | Cited 46 times

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The dynamics of photoexcited electrons in GaAs and InP were studied using the transmission of 200‐fs pulses of far‐infrared radiation in the spectral range 15–100 cm−1. Kinetic traces of the infrared transmission as a function of delay between optical excitation and infrared probe show a probe‐limited decrease in transmission followed by a more gradual (0.7–2 ps) drop to a steady value, consistent with the slow return of electrons from high‐mass satellite valleys. Infrared transmission spectra, analyzed in the context of a Drude model, reveal density‐dependent electron mobilities 3–4 times below equilibrium n‐doped values. Electron‐hole collisions likely account for the lower mobility.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.40.+w Photoconduction and photovoltaic effects

Dislocation reduction in the annealed undercut GaAs on Si

Shiro Sakai, Chun Lin Shao, Naoki Wada, Takayuki Yuasa, and Masayoshi Umeno

Appl. Phys. Lett. 60, 1480 (1992); http://dx.doi.org/10.1063/1.107277 (3 pages) | Cited 3 times

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The dislocations in the undercut GaAs on Si (UCGAS) was investigated by the cross‐sectional transmission electron microscope. The UCGAS structure was fabricated by first growing Al0.7Ga0.3As and GaAs on Si substrate and then partially etching the Al0.7Ga0.3As layer in the lateral direction. No dislocation was found in the annealed UCGAS at 800 °C for 10 min, while dislocations were observed in the region where the GaAs layer was connected to the Si substrate. The dislocation reduction mechanism in the UCGAS was also discussed in this letter.
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68.55.-a Thin film structure and morphology

Characteristics of GaAs, AlGaAs, and InGaAs materials grown by metalorganic chemical vapor deposition using an on‐demand hydride gas generator

S. G. Hummel, Y. Zou, C. A. Beyler, P. Grodzinski, P. D. Dapkus, J. V. McManus, Y. Zhang, B. J. Skromme, and W. I. Lee

Appl. Phys. Lett. 60, 1483 (1992); http://dx.doi.org/10.1063/1.107278 (3 pages) | Cited 1 time

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We report results on the properties of GaAs, AlGaAs, and InGaAs materials grown using a new, on‐demand hydride gas generator. Low pressure arsine gas is generated from an arsenic containing precursor (KAsH2) by the controlled addition of water as a chemical activator. Both generated and bottled arsine are used to grow GaAs, AlGaAs, and InGaAs structures using atmospheric pressure metalorganic chemical vapor deposition. Using generated arsine, GaAs layers with background carrier concentrations of less than n=3×1013 cm−3 were produced across a growth temperature range of 625–725 °C using a V/III ratio of 30. InGaAs grown at 640 °C with V/III=30 exhibits a background carrier concentration of n=2.5×1014 cm−3 and mobility values of μ300 K=11 350 cm2/V s and μ77 K=71 200 cm2/V s. Photoluminescence measurements show highly resolved exciton spectra using either generated or bottled arsine with donor‐bound exciton linewidths as narrow as 0.16 meV full width at half‐maximum. Broad area GaAs/AlGaAs laser devices exhibit threshold current densities as low as 195 A/cm2. The results obtained from bulk layer, quantum well structure, and broad area laser device characterization indicate that the quality of materials produced using generated arsine is equivalent or superior to that of materials produced using a high quality bottled arsine source.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.55.Cr III-V semiconductors
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