AVS 45th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS1-TuA

Paper SS1-TuA7
The Reactions of Trimethylgallium and Ammonia on GaN(0001)

Tuesday, November 3, 1998, 4:00 pm, Room 308

Session: Semiconductor Surface Chemistry
Presenter: H.-T. Lam, University of Pennsylvania
Authors: H.-T. Lam, University of Pennsylvania
J.M. Vohs, University of Pennsylvania
Correspondent: Click to Email
The reactions of trimethylgallium and ammonia on MOVPE-grown GaN(0001) were studied using temperature programmed desorption, high-resolution electron energy loss spectroscopy, Auger electron spectroscopy, and Rutherford backscattering spectrometry. The results of this study show that TMGa dissociates on GaN(0001) to form monomethylgallium (MMGa) and/or dimethylgallium (DMGa) and surface methyl groups at temperatures above 250 K. The MMGa/DMGa species either desorb between 250 and 450 K or undergo further dissociation forming adsorbed methyl groups and Ga atoms. For low TMGa coverages, surface methyl groups desorb near 600 K producing gaseous methyl radicals. At higher coverages a fraction of the methyl groups undergo dehydrogenation produces methane at 590 K and surface carbon atoms. The reaction of ammonia on GaN(0001) was found to proceed via dissociation to form surface NH@sub x@ species and atomic hydrogen above 300 K.