Free-carrier screening of polarization fields in wurtzite GaN/InGaN   laser structures
  The free-carrier screening of macroscopic polarization fields in wurtzite GaN/InGaN quantum wells lasers is investigated via a self-consistent tight-binding approach. We show that the high carrier concentrations found experimentally in nitride laser structures effectively screen the built-in spontaneous and piezoelectric polarization fields, thus inducing a ``field-free'' band profile. Our results explain some heretofore puzzling experimental data on nitride lasers, such as the unusually high lasing excitation thresholds and emission blue-shifts for increasing excitation levels. 
F. Della Sala, A. Di Carlo, P. Lugli (INFM-U Roma2), F. Bernardini   (INFM-U Cagliari), V. Fiorentini (INFM-U Cagliari, WSI ...