Electronic structures of In_1-xGa_xAs-InP strained-layer quantum wells

The band structures of In_1-xGa_xAs-InP strained-layer quantum wells are investigated theoretically in the bond-orbital model. For small x, the well material is subject to a compressive biaxial strain which lifts the HH1 subband further apart from the LH1 subband, resulting in smaller in-plane effective mass for holes. For large x, the strain becomes tensile and the LH1 subband is lifted upward with respect to the HHl subband. For x near the critical value, where the HHl and LHl energy levels cross each other, the valence-band structure undergoes a direct-to-indirect transition.