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HL: Halbleiterphysik
HL 12: Poster I
HL 12.97: Poster
Monday, March 22, 1999, 14:00–18:00, Z
Free-carrier screening of polarization fields in GaN/InGaN laser structures — •R. Scholz1, J.-M. Jancu2, F. Della Sala3, A. Di Carlo3, P. Lugli3, F. Bernardini4, and V. Fiorentini4 — 1Institut für Physik, Technische Universität Chemnitz — 2Scuola Normale Superiore, Pisa — 3Dipartimento di Ingegneria Elettronica, Università di Roma "Tor Vergata" — 4Dipartimento di Fisica, Università di Cagliari
Based on recent investigations concerning other III-V materials [1,2],
we propose an empirical self-consistent tight-binding model for
group-III nitrides and apply it to the zincblende and wurtzite crystal
modifications. The tight-binding parameters and their distance
dependences are derived from fits to self-interaction corrected LDA
pseudopotential calculations for zincblende symmetry [3]. Together
with ab initio positions of the anion and cation planes along
the wurtzite c-direction, the zincblende tight-binding parameters
result in a good fit of the wurtzite band structure. For GaN/InGaN
wurtzite heterostructures it is shown that the macroscopic
polarization field in the well region can be efficiently screened by high
free carrier densities. This reconciles some puzzling experimental data on
nitride lasers such as the high lasing excitation thresholds and the
emission blue shifts for increasing excitation levels [4].
[1] J.-M. Jancu, R. Scholz, F. Beltram, and F. Bassani, Phys. Rev. B
57, 6493 (1998).
A. Di Carlo, S. Prescetelli, M. Paciotti, P. Lugli, and M. Graf,
Solid State Commun. 98, 803 (1996).
P. Krüger, private communication.
F. Della Sala, A. Di Carlo, P. Lugli, F. Bernardini, V. Fiorentini,
R. Scholz, and J.-M. Jancu, submitted to Appl. Phys. Lett.