THERMAL-STABILITY OF SULFUR-TREATED INP INVESTIGATED BY PHOTOLUMINESCENCE

The effect of sulfur (S) treatments on InP is investigated by low-temp erature photoluminescence (PL) measurements. For both n- and p-InP, th e PL intensity is observed to increase about four times in magnitude i f the scattering by Ihs: S overlayer is relatively small. Some PL band s are observed to disappear after S treatments and then reappear if th e 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 densi ty, the doping level of the samples, and measurement temperature, thes e PL bands are ascribed to the optical transitions via surface states. Our results thus indicate that the S-treated InP surface may not be s table al a subsequent processing temperature of about 250 degrees C. ( C) 1996 American Institute of Physics.