Thermal process induced change of conductivity in As-doped ZnO

Abstract

Arsenic-doped ZnO films were fabricated by radio frequency magnetron sputtering method with different substrate temperature T S. Growing with the low substrate temperature of T S=200°C yielded n-type semi-insulating sample. Increasing the substrate temperature would yield p-type ZnO film and reproducible p-type film could be produced at T S∼ 450°C. Post-growth annealing of the n-type As-doped ZnO sample grown at the low substrate temperature (T S=200°C) in air at 500°C also converted the film to p-type conductivity. Further increasing the post-growth annealing temperature would convert the p-type sample back to n-type. With the results obtained from the studies of positron annihilation spectroscopy (PAS), photoluminescence (PL), cathodoluminescence (CL), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and nuclear reaction analysis (NRA), we have proposed mechanisms to explain for the thermal process induced conduction type conversion as observed in the As-doped ZnO films. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).