Thermal stability of sulfur-treated InP investigated by photoluminescence

The effect of sulfur (S) treatments on InP is investigated by low-temperature photoluminescence (PL) measurements. For both n- and p-InP, the PL intensity is observed to increase about four times in magnitude if the scattering by Ihs: S overlayer is relatively small. Some PL bands are observed to disappear after S treatments and then reappear if the S-treated surface is heat treated at 220 degrees C in a vacuum of 10(-3) Torr. By observing their dependence on the excitation power density, the doping level of the samples, and measurement temperature, these PL bands are ascribed to the optical transitions via surface states. Our results thus indicate that the S-treated InP surface may not be stable al a subsequent processing temperature of about 250 degrees C. (C) 1996 American Institute of Physics.