Bi-induced p-type conductivity in nominally undoped Ga(AsBi), G. Pettinari, A. Patane, A. Polimeni, M. Capizzi, X. Lu, T. Tiedje, Appl. Phys. Lett. 100, 092109 (2012)

We report p-type conductivity in nominally undoped GaAs_1-xBi_x 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 GaAs_1-xBi_x with concentration up to 2.4 x 10¹⁷  cm^-3 at x = 10.6%.