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[en] Thermal and temporal stability of electrical characteristics of III-V semiconductor materials are essential for device applications. However, it has been previously observed that Hall-effect measurements on high purity n-type InP samples grown by liquid phase epitaxial (LPE), vapor phase epitaxial (VPE), and metal-organic chemical vapor deposition techniques (MOCVD) can be changed by either aging over a long period of time at room temperature or by annealing at higher temperatures for short times. For example, after ohmic Sn contracts were made on a high purity LPE InP sample for Hali-effect measurements by alloying, the 77K carrier concentration decreased from 1.9 x 10¹⁴ cm^-3 to 5.3 x 10¹⁴ cm^-3 over a period of several months, and the 77K Hall mobility increased from 55,000 cm²/V-s to 103,000 cm²/V-s. When this aged sample was reheated to 470 degrees C for 1 minute, the mobility was reduced to 66,000 cm²/V-s. The aging effect could be explained by a decrease in the concentration of residual donor impurities either by neutralization or by a change from a shallow to deep level. However, such behaviors of residual impurities has never been observed in GaAs or in low purity InP samples. In this paper, the aging effect of high purity InP samples with different alloyed metal ohmic contacts has been investigated using Hall-effect measurements and photothermal ionization spectroscopy (PTIS). These measurements were made on aged LPE and MOCVD InP samples both before and after heat treatments

[en] The fabrication and characterization of planar, ion-implanted GaAs p-n junction photodetectors is reported. The devices were made by implanting Be ions at 250 keV to a dose of 10¹⁴cm^-2 into unintentionally doped n-type GaAs layers grown by VPE and LPE techniques on <100> oriented, n⁺ substrates. These detectors are characterized by low leakage currents (< approximately 5 nA at 0.95 V sub(br) for 250 μm diameter devices). The quantum efficiency at 8750 A is 75% for devices with junction depths of 1.2μm, p-type doping levels of 10¹⁸cm^-3, and no intentional anti-reflection coating. Avalanche gains of 10 to 15 have been measured. (author)

[en] In addition to the normally observed conduction-band--to--acceptor and ground-state-donor--to--acceptor transition peaks in the low-temperature photoluminescence spectrum of high-purity GaAs and InP, we report for the first time the observation of an additional peak in the spectrum, which we attribute to transitions from donors in their first excited state to neutral acceptors. This peak appears between the normally observed conduction-band--to--acceptor (e-A⁰) and ground-state-donor--to--acceptor (D/sub n/ = 1⁰-A⁰) peaks. The theory of Kamiya and Wagner is generalized to include this process and predicts line shapes in excellent agreement with experiment

[en] The thickness of InGaAsP (lambda/sub g/=1.15 μm) and InGaAs (lambda/sub g/=1.68 μm) liquid phase epitaxial layers grown on (100) InP substrates by the step-cooling technique has been measured as a function of growth time. (lambda/sub g/ is defined as the wavelength corresponding to the energy gap of the epitaxial layer.) For growth times much less than the shortest diffusion time tau/sub i/=l²/D/sub i/ of the melt constituents, where l is the melt height and D/sub i/ is the diffusivity of each component in the melt, the thickness is consistent with diffusion-limited theory, and the composition is constant. The time at which the growth rate deviates sharply from diffusion-limited theory and beyond which constant composition growth can no longer be maintained has been determined for the melt size used in our experiments and can be estimated for any melt size

[en] The influence of subhydride species generated in a low-pressure Ta-based AsH₃ cracker on the degree of H passivation of C acceptors in heavily doped (p≥3x10¹⁹ cm^-3) In_0.53Ga_0.47As grown by gas source and metalorganic molecular beam epitaxy has been studied. A strong correlation has been observed between the relative abundance of AsH₃, AsH, and H in quadrupole mass spectra and the degree of passivation. Enhanced effects were observed at reduced growth temperatures. Design of experiments techniques have been used to study the influence of hydride cracker temperature, substrate temperature, H₂ pumping speed, group III sources, AsH₃ flow rate and the second order interactions on the H passivation of C acceptors. The substrate temperature, hydride cracking temperature, and H₂ pumping speed, were determined to have the dominant effects, while second order interactions were dominated by substrate temperature, H₂ pumping speed, and AsH₃ flow rate interactions with the hydride cracking temperature. Optimized parameters were determined that permit the growth of essentially unpassivated (≤10%) C-doped In_0.53Ga_0.47As with net hole concentrations as high as p=8x10¹⁹ cm^-3 by both gas source and metalorganic molecular beam epitaxy techniques. copyright 1996 American Institute of Physics

[en] Efficient vapor source Si doping of InP and In_0.53Ga_0.47As have been demonstrated using SiBr₄ as the Si source for both gas source (GSMBE) and metalorganic molecular beam epitaxy (MOMBE). Net electron concentrations ranging from n=2x10¹⁷ to 6.8x10¹⁹ cm^-3 and from 9x10¹⁶ to 3x10¹⁹ cm^-3 have been obtained for InP and In_0.53Ga_0.47As, respectively. Comparison of these data with those for Si₂H₆ indicate that the Si incorporation efficiency with SiBr₄ is more than 10 000 times greater than with Si₂H₆ for substrate temperatures in the range of 475≤T_s≤500 degree C. Specular surface morphologies were obtained, even for the most heavily doped samples. While [Si] as high as 1.8x10²⁰ cm^-3 was obtained in InP, the net electron concentrations and 300 K Hall mobilities decrease with increasing [Si] for [Si]>6.8x10¹⁹ cm^-3. Contact resistances as low as R_c=3x10^-8 Ω cm² were obtained using a nonalloyed Ti/Pt/Au contact to InP layers doped to n=6.3x10¹⁹ cm^-3. During GSMBE growth, an increased Si background concentration ([Si]∼2x10¹⁷ cm^-3) was observed after extended use of the SiBr₄ source for these heavy doping concentrations. This increased background was not observed in MOMBE-grown material. Depth profiles of pulse-doped structures indicate the absence of memory effects for structures grown by MOMBE

[en] The growth of semi-insulating epitaxial InP layers at low substrate temperature (460 degree C) by low-pressure metalorganic chemical vapor deposition has been demonstrated using CCl₄ as a dopant source. The resistivity of the material is a function of diluted CCl₄ flow rate used during growth. For flow rates less than 5 sccm the material is n type, but for higher flows the resistivity of the material is approximately 5x10⁹ Ω cm. The semi-insulating behavior of the material is maintained after annealing at 600 degree C. Transmission electron microscopy does not reveal the presence of phosphorus precipitates in as-grown samples or in samples annealed at 400 and 600 degree C. There is significant carbon, hydrogen, and chlorine incorporation in the layers, as measured by secondary ion mass spectrometry. Room-temperature photoluminescence measurements suggest that nonradiative recombination is significant in the material and increases in samples grown with higher CCl₄ flows

[en] This paper discusses the use of gas sources in growth by MBE as a result of current interest in growth of InP/InGaAsP/InGaAs lattice matched to InP. For gas flows greater than a few sccm, pumping speed requirements dictate the use of turbomolecular or diffusion pumps. GaAs samples with high p-type mobilities have been grown with diffusion pumped molecular beam epitaxial system. According to the authors, this demonstration of the inherent cleanliness of a properly designed diffusion pumping system indicates that a diffusion pump is an excellent inexpensive and reliable choice for growth by molecular beam epitaxy and gas source molecular beam epitaxy/chemical beam epitaxy