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Proceedings Paper

Photoluminescence study of wurtzite Si-doped GaN thin films
Author(s): Mohammed Soltani; Cosmo Carlone; N. Sylvain Charbonneau; Shyam M. Khanna
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Paper Abstract

The photoluminescence (PL) temperature dependence of wurtzite n-type GaN thin films grown on (0001) sapphire substrates by Magnetron sputter epitaxy is reported. Samples were non-intentionally doped, lightly and highly Si-doped. The PL of non-intentionally doped samples consist of the near band edge emission and a broad yellow band (YB) near 2.2 eV. This yellow emission is equally present in spectra of all Si-doped samples. The bound exciton (D0-X) at 3.488 eV and (A0-X) at 3.456 eV are present only in the lightly Si-doped samples. The evolution of the energy position of the (D0-X) is the same as the band gap temperature variation, but the (A0-X) transition is anormally independent of the temperature in the range studied here. In both Si-doped GaN samples a peak at 3.318 eV and transitions between 3.36 and 3.39 eV are observed. The temperature dependence of the latter shows a fine structure composed of four peaks at 3.364 eV, 3.368 eV, 3.375 eV and 3.383 eV. They are tentatively attributed to the superposition of two donor-acceptor and band-acceptor transitions. This interpretation implies the presence of two donors (D1,D2) and two acceptors (A1,A2). From the energy position of the band-acceptor and the energy gap of GaN at 20 K, an acceptor ionization energy of 120 and 135 meV respectively is obtained. Assuming 10 meV for a Coulomb interaction energy of the ionized donor-acceptor pairs, a donor ionization energy of 14 and 18 meV respectively is obtained from the energy difference between the donor-acceptor and the band-acceptor positions. An activation energy of 10.8 meV is deduced from the temperature dependence of the YB. The shallow donor (about 10 meV) contributes to the mechanism of the YB.

Paper Details

Date Published: 9 October 1998
PDF: 13 pages
Proc. SPIE 3418, Advances in Optical Beam Characterization and Measurements, (9 October 1998); doi: 10.1117/12.326645
Show Author Affiliations
Mohammed Soltani, Univ. de Sherbrooke (Canada)
Cosmo Carlone, Univ. de Sherbrooke (Canada)
N. Sylvain Charbonneau, National Research Council Canada (Canada)
Shyam M. Khanna, Defence Research Establishment Ottawa (Canada)

Published in SPIE Proceedings Vol. 3418:
Advances in Optical Beam Characterization and Measurements
Michel Piche, Editor(s)

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