Dresden 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Halbleiterphysik
HL 50: Poster II
HL 50.13: Poster
Donnerstag, 30. März 2006, 16:30–19:00, P3
Transition energies and Stokes shift analysis for In-rich InGaN and InAlN alloys — •P. Schley1, R. Goldhahn1, A.T. Winzer1, G. Gobsch1, V. Cimalla2, O. Ambacher2, M. Rakel3, C. Cobet3, N. Esser3, H. Lu4, and W.J. Schaff4 — 1Institut f. Physik, TU Ilmenau — 2Institut f. Mikro- und Nanotechnologien, TU Ilmenau — 3ISAS Berlin — 4Cornell University Ithaca
We present a comprehensive optical, electrical and structural characterization of In-rich InGaN and InAlN alloys grown on sapphire substrates with either an AlN or GaN buffer layer. The absorption and emission properties of these films were studied by spectroscopic ellipsometry in the range from 0.74 up to 9.5 eV and photoluminescence spectroscopy near the band gap, respectively. Films grown on a GaN buffer layer show a much sharper increase of the imaginary part (ε2) of the dielectric function (DF) around the band gap and a slightly reduced Stokes shift compared to layers grown directly on AlN buffers. It is attributed to a reduced electron concentration and improved structural quality of the films on GaN buffers. For the determination of the band gap values as a function of alloy composition, carrier induced band gap renormalization and Burstein-Moss shift are taken into account. By fitting the third derivatives of the DF up to 9.5 eV we determined for the first time the compositional dependences (bowing parameters) of the transition energies for at least four and three critical points of the band structure for InGaN and InAlN alloys, respectively.