Control of the conduction mechanism via the formation of native defects in RF-magnetron-sputtered GaSb thin films on Ge(100) substrates

Abstract

GaSb thin films were grown on quartz substrate and Ge(100) 1°-off-axis substrate by RF magnetron sputtering at growth temperatures of 400, 500, and 600°C. The crystalline quality of GaSb/quartz improved with increasing growth temperature. The GaSb/Ge(100) grown at 500°C exhibited good crystalline quality with comparatively high mobility (219cm2/Vs); however, the mobility degraded in GaSb/Ge(100) films grown at higher temperatures because of the increase in crystal defects induced by strain relaxation. Undoped GaSb has been previously reported to always exhibit p-type conductivity, irrespective of the growth method and growth conditions. However, we prepared an undoped GaSb thin film with n-type conductivity by using a Ge(100) 1°-off-axis substrate. This finding led to the conclusion that the use of an off-axis substrate affects the defect formation mechanism and enables the control of the conduction mechanism in undoped GaSb thin films.