Sn and Si doping of α-Al2O3 (10-10) layers grown by plasma-assisted molecular beam epitaxy

Abstract

Solid-state materials with a large bandgap energy have potential for high-temperature, high-power, radiation-hardened, and ultraviolet-light applications. α-Al2O3, with a bandgap energy of ∼9 eV, is one of the most attractive such materials. However, α-Al2O3 suffers from a high resistivity. Here, we show that heavily Si-doped α-Al2O3 (100) layers grown by molecular beam epitaxy have a layer resistivity of 166 Ωcm at room temperature. We found that α-Al2O3 layers with Sn or Si concentrations over 1 × 1018 cm−3 are electrically conducting and the layer resistivity of the Si-doped α-Al2O3 layer is dramatically reduced by post-thermal annealing at 1400 °C in a N2 ambient.