Electronic band energy of a bent ZnO piezoelectric semiconductor nanowire

Abstract

The electric band energy variation in a bent piezoelectric semiconductor (PSC) nanowire of circular cross-section induced by the mechanical force is analyzed based on a six-band k · p method. The electric-mechanical fields are first obtained analytically in a cantilever bent PSC nanowire by solving the fully-coupled electro-mechanical equations. Then, the band energy is acquired numerically via the six-band Hamiltonian. By considering further the nonlinear coupling between the piezoelectric and semiconducting quantities, the contribution of the redistribution carriers to the electric field is analyzed from the Gauss’s law. Numerical examples are carried out for an n-type ZnO nanowire in different locations induced by an applied concentrated end force. These include the electric potential, heavy hole (HH), light hole (LH), spin-orbit split-off (SO), and conduction band (CB) edges along the axial and thickness directions. Our results show that the applied force has a significant effect on the band energies. For instance, on the bottom surface along the axial direction, the bandgaps near the fixed end are greater than those near the loading end, and this trend is reversed on the top surface. Moreover, at a fixed axial location, the energy level of the lower side can be enhanced by applying a bending force at the end. The present results could be of significant guidance to the electronic devices and piezotronics.