Annealing effects on the p-type ZnO films fabricated on GaAs substrate by atmospheric pressure metal organic chemical vapor deposition

Abstract

The effects of post-annealing conducted at 500-650 degrees C on structural, electrical and optical properties of ZnO film fabricated on GaAs (1 0 0) substrate by atmospheric pressure metal-organic chemical vapor deposition are investigated. X-ray diffraction analyses show that the Zn(3)As(2) and ZnGa(2)O(4) phases are produced for the specimens post-annealed at 500 degrees C and above. Hall measurements indicate that stable p-type ZnO films with hole concentration ranging from 4.7 x 10(18) to 8.7 x 10(19) cm(-3) can be obtained by modulating the annealing temperature from 500 to 600 degrees C. In particular, room-temperature photoluminescence (PL) measurements indicate that the superior-quality p-type film could be achieved by a post-annealing treatment at 600 degrees C. Moreover, low temperature PL spectra at 10 K are dominated by the acceptor-related luminescence mechanisms for the films post-annealed at 550 degrees C and above. The ionization energy of acceptor was calculated to be 133-146 meV, which is in good agreement with that theoretically predicted for the As(Zn)-2V(Zn), complex in ZnO. The interdiffused arsenic atoms in the film post-annealed at 600 inverted perpendicular C are suggested to form the As(Zn)-2V(Zn) complex quite effectively, resulting in the most enhanced p-type conductivity and improved material quality. (C) 2010 Elsevier B.V. All rights reserved.