Morphological and optical characterization of GaN prepared by pulsed laserdeposition

GaN films were grown by pulsed laser deposition (PLD on different crystalli ne substrates using a KrF excimer laser to ablate a hexagonal phase GaN tar get in a reactive atmosphere of ammonia. Films with small homogeneously dis tributed granular structures over the entire sample surface were obtained, The microstructure and surface morphology of the deposited layers were char acterized by X-ray diffraction (XRD, atomic force microscopy (AFM) and Rama n spectroscopy (RS). XRD reveals that the structure of the GaN layer is pre dominantly wurtzite. AFM images reveal that all the deposited layers have a relatively smooth surface, while RS confirmed the predominant presence of hexagonal GaN with a high polycrystalline character. Analysis of the result s obtained for samples grown under different conditions, such as the substr ate temperatures in the growth chamber as well as different substrates used , helps to define better the experimental conditions of the growth process of PLD-GaN films. (C) 2000 Elsevier Science S.A. All rights reserved.