Shifts and splitting of energy bands in elastically strained InGaP/GaAs(111)B epitaxial films

Abstract

Strain-induced shifts and splitting of energy bands are studied by optical techniques in compressively strained pseudomorphic InxGa1−xP films grown by liquid phase epitaxy on lattice-mismatched GaAs(111)B substrates. The elastic strains are measured by the x-ray diffraction technique and reach the value of 0.92%. The splitting of the valence band is revealed as a doublet in the derivative of a photocurrent spectrum which is precisely measured on the semiconductor-electrolyte interface near the fundamental absorption edge. The maximum splitting reaches 45 meV. The sublinear behavior of the valence band splitting versus elastic strain is clearly observed. This nonlinearity is explained by the interaction between the strain-split subband with J=3/2, mJ=±1/2 and the spin-orbit split subband (J=1/2, mJ=±1/2). The experimentally measured dependences of shifts and splitting on the magnitude of strain are well described by the theoretical calculations.