A research on the persistent photoconductivity behavior of GaN thin films deposited by r.f. magnetron sputtering

The persistent photoconductivity (PPC) behavior has been characterized in sputtered GaN thin films using the room illumination with a wavelength of 254 nm under a 5-V bias. It was found that the N-2 partial pressure in the sputtering atmosphere has an evident effect on the PPC behavior. The obtained data show that the nitrogen vacancy is the candidate for PPC effect in the sputtered GaN film. At lower N-2 partial pressures, the nitrogen vacancy can be induced and resulted in GaN films with more donor levels as compared with those of samples deposited at higher N-2 contents. An energy band model that can account for the experimental observation of PPC behavior is proposed. (C) 1999 Elsevier Science S.A. All rights reserved.