Pulsed laser deposition of GaN thin films

Gallium nitride thin films were grown via pulsed laser deposition (PLD) in different atmospheres (N-2, NH3 and ultra-high-vacuum) on sapphire. Resisti vity, doping and Hall mobility of the films are studied as a function of te mperature and growth conditions: we found that the films grown in ammonia h ave n-type (n approximate to 10(16) cm(-3)) background doping, while growth in N-2 (p approximate to 10(13) cm(-3)) and in UHV (p approximate to 10(19 ) cm(-3)) induces p-type doping. The surface quality of the films is also i nvestigated by atomic force microscopy (AFM) and the values for surface rou ghness are of the order of tens of nanometers for the films grown in ammoni a while films grown in N-2 have a roughness of few nanometers. (C) 1999 Els evier Science S.A. All rights reserved.