CHEMICAL BEAM EPITAXY GROWTH OF GAAS/GA0.5IN0.5P HETEROSTRUCTURES - GROWTH-KINETICS, ELECTRICAL AND OPTICAL-PROPERTIES

We report the growth kinetics, together with electrical and optical properties of undoped chemical beam epitaxy GaAs/GaInP structures grown using triethylgallium (TEGa), trimethylindium (TMIn), arsine and phosphine as starting materials for group III and group V elements. Undoped GaAs layers were found to be p-type, independent of the gallium-to-arsenic ratio, with free hole concentration ranging from 1 x 10(15) to 9 x 10(15) cm-3, depending on the growth temperature. Undoped GaAs/GaInP heterojunctions exhibit a two-dimensional electron gas with T = 4 K mobilities ranging from 20,000 to 25,000 cm2/V.s. The optical characteristics of GaAs/GaInP multiquantum wells as a function of growth interruptions at the interfaces were investigated by photoluminescence measurements. The growth kinetics of GaAs and GaInP were studied by reflection high energy electron diffraction (RHEED) oscillations. The composition of GaInP was found to be controlled mainly by the growth rate dependence of the binaries (GaP, InP) on growth parameters. The indium composition was found to be proportional to the flux of TMIn at a fixed TEGa flow. A lattice matching better than 5 x 10(-4) can be routinely obtained. However, the composition exhibits a strong dependence on temperature. At temperatures above 510-degrees-C indium desorption occurs and the composition tends toward a Ga-rich phase, while below 510-degrees-C, the indium composition is enhanced by the decrease of the binary GaP growth rate. The PH3 flow also affects significantly the ternary growth rate, mainly through indium incorporation modification. At low PH3 flow (1-5 SCCM), the indium concentration decreases. This fact is attributed to the preferential Ga-P compared to In-P bond formation.