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. © 1995 American Institute of Physics.