Abstract
Band offsets of the Al2O3/GaSb system and various surface passivation treatments of the GaSb substrate by HCl, NH4OH, and (NH4)2S solutions were investigated by x-ray photoelectron spectroscopy. The extracted conduction and valence band offsets values of Al2O3 relative to GaSb are 2.4±0.1 eV and 3.4±0.2 eV, respectively. The presence of Ga–O and Sb–O bonds was detected after NH4OH surface treatment. In contrast, (NH4)2S and HCl solutions inhibit the Sb oxide formation. The lowest amount of Ga–O bands was obtained for (NH4)2S passivation. These results correlate with capacitance-voltage (C-V) measurements of Pd–Au/Al2O3/GaSb stacks which yielded the best characteristics for the S-based passivation.
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