X-RAY PHOTOELECTRON-SPECTROSCOPY AND OPTOELECTRICAL PROPERTIES OF LOW-CONCENTRATION ERBIUM-DOPED GASB LAYERS GROWN FROM SB-RICH SOLUTIONS BY LIQUID-PHASE EPITAXY

We have attempted to grow low hole-concentration GaSb layers by introducing the rare-earth element Er into Sb-rich solutions by liquid-phase epitaxy. The x-ray photoelectron spectra suggest that the strong affinity of Er will lead to interactions between the Er and residual group-VI impurities (e.g., O, S, and Te) in the growth melt for efficient Er gettering and between the Er and the low electronegativity of group-V element Sb for the formation of stable chalcogenides. The carrier concentration of GaSb layers can be lowered due to the Er gettering and the suppression of complex acceptor defects. Intense sharp luminescence lines of free-exciton and excitons bound to neutral accepters dominate the low-temperature photoluminescence spectra. The higher breakdown voltage exhibited in the Er-doped GaSb mesa diodes is due to the reduction of carrier concentration in the Er-doped GaSb layers. (C) 1995 American Institute of Physics.