Effect of N-induced scattering centers on electron mobility in CBE grown GaAsN films

Low electron mobility causes the short diffusion length and high resistivity. To realize the tandem solar cells with high performance, the mobility must be increased. In this paper, the mechanisms that reduce electron mobility in GaAs_1-xN_x (0.0000<;x<;0.0115) were investigated from the dependence of Hall electron mobility on N composition, temperature and carrier concentration. The mobility was independent of impurity concentrations. There is a peak in the mobility as a function of temperature, such as GaAs. However, the temperature dependence changed to monotonic increase as N composition x increased to 0.0115. The increase of free carrier concentration caused improvement of the mobility at lower temperature. Hence, not ionized impurity scattering but N-related scattering was dominant scattering at low temperature. In addition, the contribution of N-related scattering became dominant comparison with alloy and phonon scattering in the higher N composition.