INTERFACE CHARACTERISTICS OF GAINP/GAAS DOUBLE HETEROSTRUCTURES GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

The formation of parasitic GaxIn1-xAsyP1-y, intermediate layers when growing GaAs on GaInP or vice versa by MOVPE is investigated by the use of asymmetric GaInP/GaAs/AlGaAs double heterostructures. We found that such intermediate layers are only formed when growing GaAs on GaInP (inverted interface), but not for the reverse case (normal interface), resulting in a strong photoluminescence peak below the GaAs band gap. Time-resolved photoluminescence also indicates a much shorter minority carrier lifetime of the structures containing the inverted GaInP/GaAs interface (similar to 10 ns) compared to samples containing the normal interface (similar to 0.5 mu s). By investigation of the interface of GaInP/AlGaAs and AlGaInP/GaAs, it is found that In carry-over is mainly responsible for the formation of this layer in our system. By growing thin AlGaAs intermediate layers (1 to 2 nm) at the inverted interface, this low-energy photoluminescence peak could be effectively suppressed. The same could be obtained without any special means in a smaller epitaxial system, probably due to the reduced hot susceptor surface.