Effect of strain on the band structure of GaAs and In0.2Ga0.8As

Abstract

The valence‐band structures of 50‐Å‐thick layers of GaAs(001) in tension and In_0.2Ga_0.8As(001) in compression have been determined using angle‐resolved photoemission spectroscopy. Our studies show that the Δ3+Δ4 bands and the Δ1 band respond differently to the strain perturbation. For strained GaAs(001), the Δ3+Δ4 bands (P_x+P_y‐like) are shifted up in energy by a maximum amount of 0.3 eV, while in contrast, the Δ1 band (P_z‐like) is shifted down by about 0.1 eV. For strained In_0.2Ga_0.8As(001), the band shifts are in the opposite direction, consistent with the opposite strain conditions. For both materials, the strain‐induced changes cannot be characterized simply by rigid band shifts, but rather exhibit significant wave vector dependence. This results in a reduction of the effective mass of the Δ3+Δ4 bands for both GaAs and In_0.2Ga_0.8As.