PHOSPHORUS-VACANCY-RELATED DEEP LEVELS IN GAINP LAYERS

Deep levels in lattice‐matched Ga0.51In0.49P/GaAs heterostructure have been investigated by thermal‐electric effect spectroscopy (TEES) and temperature‐dependent conductivity measurements. Four samples were grown by molecular‐beam epitaxy with various phosphorus (P2) beam‐equivalent pressures (BEP) of 0.125, 0.5, 2, and 4×10−4 Torr. A phosphorus vacancy (VP) ‐related deep level, an electron trap, was observed located at EC−0.28±0.02 eV. This trap dominated the conduction‐band conduction at T≳220 K and was responsible for the variable‐range hopping conduction when T<220 K. Its concentration decreased with the increasing phosphorous BEP. Successive rapid thermal annealing showed that its concentration increased with the increasing annealing temperature. Another electron trap at EC−0.51 eV was also observed only in samples with P2 BEP less than 2×10−4 Torr. Its capture cross section was 4.5×10−15 cm2. This trap is attributed to VP‐related complexes.