Electrical properties of n-type AlGaN with high Si concentration

Abstract

The electrical properties of Si-doped AlGaN layers (AlN molar fractions: 0.03–0.06) with the donor concentrations (ND) from 8.8 × 1017 to 4.5 × 1020 cm−3 were investigated by variable-temperature Hall effect measurement using the van der Pauw method. A minimum resistivity of 3.6 × 10−4 Ω cm was obtained for Si-doped AlGaN with a smooth surface at room temperature. We found that the activation energy of the Si donor is affected by the Coulomb interaction in the AlGaN layer with ND values from 8.8 × 1017 to 2.5 × 1020 cm−3. In several AlGaN layers, the free-electron concentration did not vary with sample temperature, as expected in the case of degeneracy. The localization of GaN in the AlGaN layer was speculated as a cause of degeneracy of samples.