Electron effective mass in gallium antimonide determined by faraday rotation measurements

Abstract

The two-band model is used to calculate the electron effective mass in the [000] conduction band of n-type GaSb using values of the free carrier Verdet coefficient and Hall coefficient measured at 77°K and 296°K. The effective mass was found to be m ∗ = (0.049 +0.005 −0.003) m e for a sample having a carrier concentration of 3.77 × 10 17 cm −3 in the [000] band and a ratio of the electron mobilities in the two bands of μ 1 μ 0 = 1 6 . The separation between the [000] and 〈111〉 minima increases with temperature at a rate of +1.1 × 10 −4 eV °K −1. The density-of-states mass ratio is found to be m d1 m d0 = 14.3. The interband Faraday rotation at the edge indicates a temperature dependence of the direct optical gap in the degenerate n-type sample: Δ E opt/Δ T = Δ E g /Δ T−4 k, where E g is the direct energy gap and k is the Boltzmann constant.