Pulsed laser deposition of GaN thin films

Abstract Gallium nitride thin films were grown via pulsed laser deposition (PLD) in different atmospheres (N 2 , NH 3 and ultra-high-vacuum) on sapphire. Resistivity, doping and Hall mobility of the films are studied as a function of temperature and growth conditions: we found that the films grown in ammonia have n-type ( n ≈10 16 cm −3 ) background doping, while growth in N 2 ( p ≈10 13 cm −3 ) and in UHV ( p ≈10 19 cm −3 ) induces p-type doping. The surface quality of the films is also investigated by atomic force microscopy (AFM) and the values for surface roughness are of the order of tens of nanometers for the films grown in ammonia while films grown in N 2 have a roughness of few nanometers.