| Summary: | 碩士 === 逢甲大學 === 電機工程所 === 93 === Abstract
The relationship between the surface states related to nitrogen -vacancy defects and surface Fermi level pinning has been investigated using x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and capacitance–voltage measurements. Barrier heights of 1.09, 0.50, 1.20, and 0.5eV, respectively, were obtained for Ni/(NH4)2Sx-treated n-GaN, Ni/etched n-GaN, Au/(NH4)2Sx-treated n-GaN and Au/etched n-GaN Schottky diodes. For Schottky diodes with (NH4)2Sx treatment, the observed Schottky barrier height is very close to the Schottky limit, due to the reduction of the surface state density. This suggests that a large number of surface states related to nitrogen-vacancy defects on the etched n-GaN surface would lead to the pinning of the Fermi level at 0.50eV below the conduction band edge.
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