Band offsets of atomic-layer-deposited Al2O3 on GaAs and the effects of surface treatment.
Nhan V. Nguyen, Oleg A. Kirillov, Weirong Jiang, Wenyong Wang, John S. Suehle, P. D. Ye, Y. Xuan, N. Goel, Kwang-Woo Choi, Wilman Tsai
In this letter we report the band offsets of the Al/Al2O3/GaAs structure determined by internal photoemission and spectroscopic ellipsometry. The energy barrier height at the Al2O3 and sulfur-passivated GaAs interface is found to be 3.0 eV, which is different from those obtained on unpassivated or NH4OH-treated GaAs. At the Al metal gate and Al2O3 interface, all samples yield the same zero-field barrier height of 2.9 eV. With an optical band gap of 6.4 eV for thin Al2O3 determined from spectroscopic ellipsometry, the band alignments at both Al2O3 interfaces can be configured.
Applied Physics Letters
Internal Photoemission Spectroscopy, Al/Al<sub>2</sub>O<sub>3</sub>/GaAs devices, band offsets, band alighments, ellipsometry, band gap