Effects of ordering on the electron effective mass and strain deformation potential inGaInP2: Deficiencies of thek⋅pmodel

The conventional eight-band k⋅p model predicts a decrease of the electron effective mass and no dependence of the (001) strain band-gap deformation potential with the degree η of long-range order in ${\mathrm{Ga}}_{0.5}$ ${\mathrm{In}}_{0.5}$P alloys. We show that a complete band-structure approach predicts instead that (i) the electron effective mass in the ordering direction increases from 0.092${\mathit{m}}_0$ for η=0 (random alloy) to 0.133${\mathit{m}}_0$ for η=1 (ordered alloy), and (ii) the strain deformation potential decreases in magnitude from 8.26 eV for η=0 to 6.34 eV for η=1. These two effects are caused by the mixing of the conduction-band minimum with the L-derived conduction band, neglected in the standard eight-band model.