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Münster 1999 – scientific programme

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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. Fiorentini41Institut 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.

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