Band offsets of atomic-layer-deposited Al2O3 on GaAs and the effects of surface treatment

The metal gate/high-k dielectric/III-V semiconductor band alignment is one of the most technologically important parameters. We report the band offsets of the Al/Al(2)O(3)/GaAs structure and the effect of GaAs surface treatment. The energy barrier at the Al(2)O(3) and sulfur-passivated GaAs interface is found to be 3.0 +/- 0.1 eV whereas for the unpassivated or NH(4)OH-treated GaAs is 3.6 eV. At the Al/Al(2)O(3) interface, all samples yield the same barrier height of 2.9 +/- 0.2 eV. With a band gap of 6.4 +/- 0.05 eV for Al(2)O(3), the band alignments at both Al(2)O(3) interfaces are established. (C) 2008 American Institute of Physics.