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 introd ucing the rare-earth element Er into Sb-rich solutions by liquid-phase epitaxy. The x-ray photoelectron spectra suggest that the strong affi nity 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 E r gettering and between the Er and the low electronegativity of group- V element Sb for the formation of stable chalcogenides. The carrier co ncentration of GaSb layers can be lowered due to the Er gettering and the suppression of complex acceptor defects. Intense sharp luminescenc e lines of free-exciton and excitons bound to neutral accepters domina te the low-temperature photoluminescence spectra. The higher breakdown voltage exhibited in the Er-doped GaSb mesa diodes is due to the redu ction of carrier concentration in the Er-doped GaSb layers. (C) 1995 A merican Institute of Physics.