We have investigated the N composition, $x$, and temperature, $T$, dependence of the electron effective mass, $m^{\ast }$, of ${\text{GaAs}}_{1-x}{\text{N}}_x$ films with sufficiently low carrier concentration that carriers are expected to be confined to near the bottom of the conduction-band edge (CBE). Using Seebeck and Hall measurements, in conjunction with assumptions of parabolic bands and Fermi-Dirac statistics, we find a nonmonotonic dependence of $m^{\ast }$ on $x$ and an increasing $T$ dependence of $m^{\ast }$ with $x$. These trends are not predicted by the two-state band anticrossing model but instead are consistent with the predictions of the linear combination of resonant nitrogen states model, which takes into account several N-related states and their interaction with the GaAs CBE.

• Received 3 February 2010
• Corrected 20 October 2010

DOI:https://doi.org/10.1103/PhysRevB.82.125203