Uniaxial stress dependence of the properties of the DX center in n‐Al0.32Ga0.68As

We have measured the emission energy, Ee, and the capture energy, Ec, and derived the thermal activation energy of the DX center, EDX, in n‐Al0.32Ga0.68As as a function of uniaxial stresses along the 〈100〉 and the 〈111〉 directions. We found that the stress coefficients of EDX change sign when the band gap of Al0.32Ga0.68As changes from direct to indirect for both stress directions, and the stress coefficients of EDX in the indirect region are about same for both stress directions. These results agree with the model proposed by Chadi and Chang which assumes that the DX center is a highly localized center and disagree with the model which takes the DX center to be the effective‐mass state associated with the L minima.