Influence of bismuth incorporation on the valence and conduction band edges of GaAs1-xBix

We investigate the electronic properties of GaAs(1-x)Bi(x) by photoluminescence at variable temperature (T=10-430 K) and high magnetic field (B=0-30 T). In GaAs(0.981)Bi(0.019), localized state contribution to PL is dominant up to 150 K. At T=180 K the diamagnetic shift of the free-exciton states reveals a sizable increase in the carrier effective mass with respect to GaAs. Such an increase cannot be accounted for by an enhanced localized character of the valence band states, solely. Instead, it suggests that also the Bloch states of the conduction band are heavily affected by the presence of bismuth atoms. (C) 2008 American Institute of Physics.