Valence subband structures of (101̄0)-GaN/AlGaN strained quantum wells calculated by the tight-binding method

The effect of biaxial strain on the valence bands in (101̄0)-GaN/AlGaN quantum wells (QWs) is theoretically investigated, using the sp3 tight-binding method. The effective mass around the valence band edge in unstrained (101̄0) QWs is reduced to about 1/2 that of (0001) QWs. Under compressive strain, the subband non-parabolicity near the band edge is further reduced due to heavy-hole/light-hole splitting. The optical matrix elements of [112̄0] polarization in these QWs are twice as large as those in (0001) QWs. The reduced effective mass and large optical matrix elements in the (101̄0) QWs are an advantage for short-wavelength laser diodes based on wurtzite GaN.