Analysis of GaN Ultrathin Films grown by Direct Ion Beam Deposition

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In the contribution, the in-situ analysis of GaN ultrathin films grown on Si (111) by a low-temperature technique combining a hyperthermal nitrogen ion beam and gallium atomic beam under UHV conditions will be presented. Low energy ions from the beam (10 -100 eV) provides an extra kinetic energy on the surface, thus substituting a need for higher temperatures typical for other techniques (e.g. MOCVD). Additionally, this extra energy is responsible for a subsurface growth improving the layer adhesion. Deposition experiments were carried out at different operation parameters. The dependence on ion-impact energy, substrate temperature and ion-to-atom arrival ratio was examined. The ultrathin films were analyzed using XPS to find their composition, their structure- and morphology analyses were carried out by LEED and AFM, respectively. Compared to our previous experiments, the deposition setup was improved by modification of a gas distribution system and by application of nitrogen of higher purity (6-9). The former allowed us to bake up the whole vacuum apparatus including the high-energy ion source chamber and transport optics. It resulted in the higher purity of ion beam and, hence, in better conditions for deposition of clean oxygen-free GaN films.

Gallium; GaN; direct deposition

VOBORNÝ, S.; MACH, J.; POTOČEK, M.; KOSTELNÍK, P.; ČECHAL, J.; BÁBOR, P.; SPOUSTA, J.; ŠIKOLA, T.

25. 9. 2005

Vienna

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