Significance of third-order elasticity for determination of the pressure coefficient of the light emission in strained quantum wells

We investigate the contribution arising from third-order elasticity to the pressure coefficient of the light emission (dE(E)/dP) in strained zinc-blende InGaAs/GaAs and InGaN/GaN quantum wells (QWs) grown in a (001) direction. In the framework of the third-order elasticity theory, we develop a model of pressure tuning of strains in these structures, which is then used to determine the coefficient dE(E)/dP. In the calculations of dE(E)/dP, we use a consistent set of the second- and third-order elastic constants which has been obtained from ab initio calculations. Our results indicate that the usage of third-order elasticity leads to significant reduction in dE(E)/dP in strained (001)-oriented InGaAs/GaAs and InGaN/GaN QWs, in comparison to the values of dE(E)/dP obtained by using the linear theory of elasticity. In the case of InGaAs/GaAs QWs, the values of dE(E)/dP calculated using third-order elasticity are in reasonable agreement with experimental data. For InGaN/GaN QWs, better agreement between theoretical and experimental values of dE(E)/dP is obtained when instead of third-order elasticity, pressure dependence of the second-order elastic constants is taken into account.