Bi-induced <i>p</i>-type conductivity in nominally undoped Ga(AsBi)

Abstract

We report p-type conductivity in nominally undoped GaAs1–xBix epilayers for a wide range of Bi-concentrations (0.6% ≤ x ≤ 10.6%). The counterintuitive increase of the conductivity with increasing x is paralleled by an increase in the density of free holes by more than three orders of magnitude in the investigated Bi-concentration range. The p-type conductivity results from holes thermally excited from Bi-induced acceptor levels lying at 26.8 meV above the valence band edge of GaAs1−xBix with concentration up to 2.4 × 1017 cm−3 at x = 10.6%.