DEEP ACCEPTOR-LIKE STATES IN SI DOPED MOLECULAR-BEAM-EPITAXIAL-GROWN ALXGA1-XAS

Acceptorlike states with energy levels in the lower part of the band g ap have been observed by photocapacitance measurements in Si-doped mol ecular-beam-epitaxial-grown AlxGa1-xAs (x=0.30-0.59), The microscopic structure of these defects is still unclear. Their concentration, howe ver, can exceed the net donor concentration. The energy positions of t he acceptorlike states as well as their photoionization cross sections ,of holes and electrons have been studied for different x. Due to thei r large concentration, these states may disturb experiments performed on DX centers which are often assumed to be the main electronic levels in these materials. (C) 1996 American Institute of Physics.