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

Abstract

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 $\text{Al}/{\text{Al}}_2{\text{O}}_3/\text{GaAs}$ structure and the effect of GaAs surface treatment. The energy barrier at the ${\text{Al}}_2{\text{O}}_3$ and sulfur-passivated GaAs interface is found to be $3.0\pm 0.1\text{eV}$ whereas for the unpassivated or ${\text{NH}}_4\text{OH}$ -treated GaAs is 3.6 eV. At the $\text{Al}/{\text{Al}}_2{\text{O}}_3$ interface, all samples yield the same barrier height of $2.9\pm 0.2\text{eV}$ . With a band gap of $6.4\pm 0.05\text{eV}$ for ${\text{Al}}_2{\text{O}}_3$ , the band alignments at both ${\text{Al}}_2{\text{O}}_3$ interfaces are established.