AVS 50th International Symposium
    Semiconductors Monday Sessions
       Session SC-MoM

Paper SC-MoM4
Ion-Beam-Assisted Molecular Beam Epitaxy of GaN

Monday, November 3, 2003, 9:20 am, Room 321/322

Session: Heteroepitaxy of Wide Bandgap Semiconductors
Presenter: B. Cui, University of Minnesota
Authors: B. Cui, University of Minnesota
I.P. Steinke, University of Minnesota
P.I. Cohen, University of Minnesota
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Energetic particles, such as photons and ion beams have been widely used to assist semiconductor thin film deposition.@footnote 1,2@ High quality GaN can only be obtained in high growth temperature both for MOCVD and MBE. IBAD provides us with a powerful tool to control the growth kinetics and to grow GaN at relatively low temperatures. In this study, sub-keV ion beams from a 3-cm Kaufman source have been applied at a glancing angle to assist the growth of GaN in a MBE system. Basal plane sapphire and MOCVD GaN templates were used as the substrates. Ga was provided by a thermal effusion cell. Ammonia was used as the nitrogen source. Before growing GaN, the sapphire substrates were pretreated in an ion flux and then annealed for cleaning. The sapphire surface was then nitrided in ammonia at 1100K for about 10 min. After nitridation, a thin GaN buffer layer was prepared by a sequence of adsorption and annealing steps. During the growth, the surface roughness and film quality were monitored in situ using light scattering and RHEED. The height-height correlation functions were obtained from diffraction pattern to quantitatively analyze the surface roughness during growth. The results were compared with that obtained by AFM images. Different ion species, including hydrogen, nitrogen, and argon, were used to study the roles of momentum transfer, energy transfer, and ion reactivity on the evolution of surface morphology. A simplified ion-adatom energy transfer model was used to interpret the results. Partially supported by the National Science Foundation and the Air Force Office of Scientific Research. @FootnoteText@ @footnote 1@R. L. Headrick, et al. Phys. Rev. B 58, 8 4818 (1998) @footnote 2@J. Erlebacher, et al. Phys. Rev. Lett. 84, 25 5800 (2000).