Optical study of APCVD-grown Si 1− xGe x/Si quantum well structures under different post-growth annealing conditions

Abstract

Single and double Si 1− x Ge x /Si quantum well (QW) structures, which were grown by atmospheric pressure chemical vapor deposition (APCVD), are characterized by photoluminescence and secondary-ion mass spectrometry. Systematic post-growth annealing treatments are carried out at temperatures between 600 and 1100°C in pure N 2 ambient. The interdiffusion between the Si layer and the Si 1− x Ge x well layers occurs at the annealing temperature around 900°C. From SIMS measurements for single QW structures we have estimated the activation energy which is about 3.9 eV in the temperature range between 950°C and 1100°C. The double QW structures show a similar value. The intensity of the exciton recombination related to carriers confined in the double QW structures decreases with increasing annealing temperatures and becomes strongly suppressed at 750°C. When the annealing temperature is increased further, the intensity of the QW emission recovers in the QW structures.