Effect of spontaneous and piezoelectric polarization on intersubband transition in Al_xGa_(1-x)N-GaN quantum well

摘要

A self-consistent solution of conduction band profile and subband energies for Al_xGa_(1-x)N-GaN quantum well is presented by solving the Schroedinger and Poisson equations. A new method is introduced to deal with the accumulation of the immobile charges at the Al_xGa_(1-x)N-GaN interface caused by spontaneous and piezoelectric polarization in the process of solving the Poisson equation. The effect of spontaneous and piezoelectric polarization is taken into account in the calculation. It also includes the effect of exchange-correlation to the one electron potential on the Coulomb interaction. Our analysis is based on the one electron effective-mass approximation and charge conservation condition. Based on this model, the electron wave functions and the conduction band structure are derived. We calculate the intersubband transition wavelength λ_(21) for different Al molar fraction of barrier and thickness of well. The calculated result can fit to the experimental data well. The dependence of the absorption coefficient a on the well width and the doping density is also investigated theoretically.