Transport and response properties of non-equilibrium steady state semiconductor quantum well structures

This thesis is to investigate the transport and response properties of non-equilibrium steady state semiconductor quantum well structures. Quantum well structures operating under bias in a non-equilibrium steady state with appropriate carrier injection and extraction are the best candidates to generate terahertz (THz) radiation via plasma instabilities.; A fully self-consistent computational scheme is set up. The non-equilibrium steady state is determined by Hartree method or Kohn-Sham density functional theory method. The injection-extraction rates are determined by the transfer matrix method or eigenvalue method. The inter-subband electron-electron collision rates and inter-subband electron-LO phonon collision rates are also considered. The subband population is determined by the current balance equations which are based on several models. The plasma response theory is given for the bounded system. The current-voltage characteristics are calculated and compared with experimental results. Good agreements are obtained for 2 different quantum well structures. The response properties are also calculated and a higher plasma instability growth rate is obtained in a higher doping structure. Further works are suggested.