No abstract

The availability of automated techniques makes possible very detailed characterization of III-V epitaxial layers. We report results of a study of the growth of indium phosphide and indium gallium arsenide layers on 50 mm diam indium phosphide substrates by trichloride vapor phase epitaxy under a variety of conditions and some effects of reactor parameters on the growth process from a wafer-scale point of view. It is shown that the patterns of variation observed in twodimensional wafer-scale growth rate maps can be correlated with data obtained from series of runs in which conditions were systematically varied. The results are interpreted in terms of the underlying physics and chemistry of the growth process.

The first experimental evidence of an isolated self-interstitial defect in an as-grown semiconductor is reported. An optically detected magnetic resonance spectrum observed in GaP [0] was identified as arising from a Ga selfinterstitial. The large isotropic hyperfine splittings (g = 2.003 (3), A(69Ga) = 741(5)×10−4 cm−1 and A(71Ga) -941[5]×10− 4 cm−1) revealed that a single Ga atom at a Td-symmetric site is the center of the defect. The interstitial nature is established by theoretical considerations. The spin dependent recombination process is attributed to a non-radiative donor-acceptor-pair process involving the Ga++ state which is in competition with a radiative (Odeg; - A° ) pair process and an electron capture process at O-donor.

Two problems facing MOCVD grown GaAs-on-Si are firstly, scale up to 3” and greater wafer diameter with acceptably uniform layer thicknesses and electrical and optical properties, and secondly the achievement of adequate device isolation through the use of buffer layers of low doping density (≤1014 cm−3). We have investigated the thickness uniformity and 300K photoluminescence intensity of 3” Ø, MOCVD grown GaAs layers on Si substrates by whole wafer mapping of these parameters, and correlate the variations found with the gas flow direction during deposition of the GaAs. We have overcome the high background doping densities (n =5−20 × 1015 cm2) in the material by a buried Be implant (1−5 × 1012 at 120 keV) followed by 850°C, 3 sec annealing. This provides adequate isolation for MESFETS and we fabricated such devices with gm's of 160-175 mS mm−1 using our standard process. These values are similar to homoepitaxial MESFETS fabricated in the same way.