High quality GaxIn1−xP (x = 0.65, 0.69) grown by OMVPE

Abstract

High quality epitaxial layers of Ga x In 1- x P ( x = 0.65, 0.69) have been grown by the organometallic vapour phase epitaxy (OMVPE) technique using trimethylgallium (TMGa), trimethylindium (TMIn) and phosphine (PH 3 ) in an atmospheric pressure reactor. These epilayers of Ga x In 1- x P were lattice-matched to GaAs 0.70 P 0.30 (for x = 0.65) and GaAs 0.61 P 0.39 (for x = 0.69). The growth rate was as large as 12 μm/h, and the growth efficiency was also high, 5.2x10 3 μm/mol. The Ga distribution coefficient was found to be 1.24, or nearly unity. The influence of the V/III ratio on surface morphology and photoluminescence (PL) intensity was investigated. For a growth temperature of 625°C, high values of V/III ratio, > 40, were necessary for the growth of epilayers with good surface morphologies and high PL intensities. The quality of the epilayers was determined by observation of surface morphology, dislocation etch pit densities, and PL measurements. Smooth interfaces and featureless surface morphologies were obtained reproducibly. The average dislocation etch pit density for the Ga 0.69 In 0.31 P epilayers was 7.4x10 4 cm -2 , one order of magnitude less than the 6.4x10 5 cm -2 of the GaAs 0.61 P 0.39 substrates. The PL half-widths of 43 meV at 300 K and 18 meV at 8 K are comparable to the best results reported to date. The relation between PL intensity and solid composition, x , was studied. It was found that the direct-indirect cross-over point for Ga x In 1- x P is x = 0.69.