Band offsets determination and interfacial chemical properties of the Al_2O_3/GaSb system

摘要

Band offsets of the Al_2O_3/GaSb system and various surface passivation treatments of the GaSb substrate by HC1, NH_40H, and (NH_4)_2S solutions were investigated by x-ray photoelectron spectroscopy. The extracted conduction and valence band offsets values of AI_2O_3 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 NH_40H surface treatment. In contrast, (NH_4)_2S and HC1 solutions inhibit the Sb oxide formation. The lowest amount of Ga-0 bands was obtained for (NH_4)_2S passivation. These results correlate with capacitance-voltage (C-V) measurements of Pd-Au/Al_2O_3/GaSb stacks which yielded the best characteristics for the S-based passivation.