Abstract: The piezoelectric coefficients of all the binary III-N wurtzite semiconductors for both first and second order has been used to evaluate the impact of non linear piezoelectricity on quantum wells and quantum dots of III-N materials and its alloys. The often neglected second order coefficients have instead significant effects on the strain induced piezoelectric polarization. The comparison of our predictions with the experimentally obtained values reveals a much better match with the internal piezoelectric fields in quantum wells and superlattices. The impact of our semi empirical approach is quite pronounced in III-N quantum dots as the excitonic properties remain highly influenced.
Abstract: First- and second-order piezoelectric coefficients for all binary group-III nitride (III-N) wurtzite semiconductors are calculated using ab initio density functional theory. The method used allows the simultaneous determination of spontaneous and strain-induced polarization within the same framework. Although the linear coefficients are similar to all existing values reported in the literature, all spontaneous polarization terms are substantially smaller than the currently proposed values. Second-order coefficients also change the total strain-induced polarization significantly. We compare the predictions obtained using these coefficients with data in superlattice structures comprising binary nitride semiconductors and by including composition dependence with all available experimental data on III-N ternary alloys. We show that, unlike existing models, our calculated piezoelectric coefficients and nonlinear model provide a close match to the internal piezoelectric fields of quantum well and superlattice structures.
Abstract: The elastic and dielectric properties of binary III-N wurtzite semiconductors have been investigated as a function of strain. Using an ab initio density functional theory (DFT), we concentrate on the internal displacement (u) and Born effective charge (Z*) and show that our model provides a unique non linear dependence of the III-N material properties as a function of strain.
Abstract: We investigate the strain dependence of piezoelectric effect, both linear and non linear, in zincblende GaAs and InAs semiconductors. We expanded the polarization in terms of the ionic and dipole charges, internal displacement and the exploited the ab-initio Density Functional Theory (DFT) to evaluate the dependence of all quantities on the strain tensor. By this detailed study of the non linear piezoelectric effect, we report that even third order effects are significant.
Abstract: Abstract: We investigate the effects of linear and non linear piezoelectricity in wurtzite III-N semiconductors and their influence on the electronic properties of low dimensional quantum dots. By studying the dependence of the biexciton on structural and geometrical parameters of the nanostructure, we show second order to be important particularly when the strain in the nanostructure is reduced.
