Effect of Rapid Thermal Annealing on Al Doped n-ZnO Films Grown by RF-Magnetron Sputtering

High-quality Al-doped n -type ZnO ( n -ZnO:Al) epilayers have been grown by an rf-magnetron sputtering technique combined with a rapid thermal annealing (RTA) process. The electrical and optical properties of as-deposited samples are considerably improved upon annealing at 900°C for 3 min in nitrogen ambient. The improvement is attributed to the deoxidation of Al-oxides, i.e., the activation of Al dopants. The samples annealed at 900°C produce a mobility of 65.5 cm 2 /V·s and a carrier concentration of 1.03×10 20 cm -3 . It is also shown that the sample surface becomes significantly smoother after annealing. The results show that the RTA process effectively improves the electrical and optical properties of the Al-doped ZnO films.