Tuning electronic energy band in a piezoelectric semiconductor rod via mechanical loading

Based on the k·p model with 8 × 8 band Hamiltonian, we demonstrate that the electronic energy band in a wurtzite piezoelectric semiconductor (PSC) rod can be tuned by a pair of uniaxial mechanical tractions. This tuning is achieved by solving two sub-problems: the electro-mechanical fields induced by a pair of axial tractions applied at the two ends of the rod, and the band energy based on the calculated strains and electric potential via the k·p model. Numerical results indicate that, when the magnitude of the applied load is relatively small, the induced PSC fields predicted by the linear model in the rod generally agree with those based on the present rigorous nonlinear model. Otherwise, the linear model will be invalid and the present nonlinear model has to be used to characterize correctly the intrinsic nonlinear property in the PSC rod. It is the first time that the heavy hole (HH), light hole (LH), spin-orbit split-off (SO) and conduction band (CB) in ZnO and GaN rods are all analyzed in details at different locations of the rod under different magnitudes of the applied traction. It is shown that the mechanical load could significantly affect the energy band edges, particularly near the ends of the rod where the loads are applied. Furthermore, the coupling effect of the valence band (VB) and CB is discussed in an InN rod where the material has a narrow bandgap. This work provides a unique opportunity in nanodevice design where nano energy is a key parameter.