Optical Absorption due to Inter-Conduction-Minimum Transitions in Gallium Arsenide

The infrared absorption in $n$-type GaAs has been studied as function of carrier concentration, temperature, and uniaxial stress. The data have established that the lowest secondary minima are located at the Brillouin-zone edge along $\mathbf{k}\parallel 〈001〉$, 0.43±0.015 eV above the k=0 minimum at 80°K. An observed structure near 0.7 eV has been assigned to transitions into a higher-lying $〈100〉$ minima 0.78±0.05 eV above the primary minimum. The spectra revealed no evidence of transitions to $〈111〉$ minima.