Advances in Pulsed Laser Deposition growth of nitride thin films

Pulsed Laser Deposition of nitride semiconductor films offers an alternative to more usual techniques, such as MOCVD and MBE. PLD can produce good quality films at reduced growth temperatures. Rapid progress has been achieved in the last few years, including demonstrations of epitaxial growth of GaN directly on sapphire. Work on PLD of direct-transition III-nitrides is briefly reviewed and our recent results for these materials are presented. Growth of these nitrides requires provision of nitrogen in a reactive form, which is usually supplied by NH3 gas flow. With the approach described here, reactive nitrogen is provided in an atomic beam, which has the advantage of reducing dependence on substrate temperature to surmount the kinetic energy barrier for formation, while eliminating a source of hydrogen during growth. Films grown from ceramic GaN targets are compared with those grown from liquid Ga. The latter method can offer better control of unintentional doping. InN films were also grown directly from In metal targets, with very good results in terms of stoichiometry and crystalline quality. AlN films were grown from ceramic AlN targets, with excellent texture at reduced temperatures. Results are presented for crystal structure (with both in-plane and off-plane XRD), composition, and surface morphology. Optical properties were studied by transmission and luminescence spectroscopy.