ORGANOMETALLIC VAPOR-PHASE EPITAXIAL-GROWTH OF A NEW QUATERNARY SEMICONDUCTOR ALLOY GA1-XINXP1-YSBY

Quaternary Ga1-xInxP1-ySby alloys have been grown for the first time by atmospheric pressure organometallic vapor phase epitaxy (AP-OMVPE) in a horizontal, infrared-heated reactor using trimethylgallium, trimethylindium trimethylantimony, and phosphine as the source materials. In general, epilayers with good surface morphologies were obtained. Growth temperatures between 480 and 560°C were used because of the low melting temperatures of these alloys. At the lower end of this range, Ga incorporation was found to decrease with decreasing temperature. Furthermore, the presence of Sb in the growth process also caused a decrease of the Ga distribution coefficient. Optical characterization was carried out using low temperature photoluminescence, photoluminescence excitation, and transmission spectroscopies. Quaternary alloys with 10 K energy band gaps ranging from 0.21 to 1.98 eV (5.9 to 0.63 μm) were grown on GaAs, InP, GaSb, InAs, and InSb substrates. The band gap energies were found to be in good agreement with the results of earlier calculations. However, 10 K photoluminescence of Ga1-xInxP1-ySby with higher band gaps was routinely observed with peak energies about 90 to 140 meV lower than the band gap energies. This may be due to either donor-acceptor pair recombination or, perhaps, recombination involving tail states produced by compositional fluctuations in these highly metastable alloys. Smaller band gap alloys have peak energies lower than the values of band gap by about 20 to 110 meV. © 1990.