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We have used cross-sectional micro-Auger electron spectroscopy (AES), coupled with micro-cathodoluminescence (CLS) spectroscopy, in a UHV scanning electron microscope to probe the chemical and related electronic features of hydride vapor phase epitaxy GaN/sapphire interfaces on a nanometer scale. AES images reveal dramatic evidence for micron-scale diffusion of O from Al2O3 into GaN. Conversely, plateau concentrations of N can extend microns into the sapphire, corresponding spatially to a 3.8 eV defect emission and Auger chemical shifts attributed to Al-N-O complexes. Interface Al Auger signals extending into GaN indicates AlGaN alloy formation, consistent with a blue-shifted CLS local interface emission. The widths of such interface transition regions range from ≪100 nm to ∼1 μm, depending on surface pretreatment and growth conditions. Secondary ion mass spectroscopy depth profiles confirm the elemental character and spatial extent of diffusion revealed by micro-AES, showing that cross-sectional AES is a useful approach to probe interdiffusion and electronic properties at buried interfaces.


Copyright © 2004, American Vacuum Society. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Association of Physics Teachers. The following article appeared in the Journal of Vacuum Science & Technology A, and may be found at



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