Band structure of InGaP from pressure experiments

Abstract

Positive identification of the Γ and X conduction‐band minima in InGaP has been made by performing hydrostatic‐pressure experiments on forward‐biased p‐n junction diodes. The Γ and X valleys are coincident in energy at a composition of In_0.37Ga_0.63P, and the corresponding bandgap is (2.17±0.02) eV at 300°K. The indirect bandgap E_X in InP is inferred from the measurements to be 2.0 eV at 300°K. In addition, the pressure coefficients of the direct and indirect bandgaps, ∂E_Γ∕∂P and ∂E_X∕∂P, respectively, have been measured at various In(1−x)GaxP compositions. For InP, ∂EΓ∕∂P is 8.7×10−3 eV∕kbar and this coefficient increases to 13×10⁻³ eV∕kbar for compositions close to In_0.5Ga_0.5P. On the other hand, ∂E_X∕∂P = −1.25×10⁻³ eV∕kbar for GaP and shows little change for compositions in the range 0.4<x<1. The deformation potential is 5.7 eV for the Γ valley in InP, and increases to about 9 eV for direct bandgap ternary compositions.