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Proceedings Paper

Exciton-polariton propagation in AlGaN/GaN quantum-well waveguides probe by time-resolved photoluminescence
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Paper Abstract

The propagation properties of light in AlGaN/GaN multiple- quantum-well (MQW) waveguides have been studied by time- resolved photoluminescence (PL) spectroscopy. The waveguides were patterned with fixed width of 0.5micrometers but orientations varying from -30 degree(s) to 60 degree(s) relative to the a-axis of GaN by electron-beam lithography and inductively-coupled plasma (ICP) dry etching. The peak position and line-width of the emission peak were found to vary systematically with orientations of the waveguides and followed the six-fold symmetry of the wurtzite structure. This is explained in terms of anisotropy of the exciton/carrier diffusion coefficient along the different crystal orientations of the semiconductor materials. We also observed a remarkable decrease in the PL intensity as well as increase in time delay of the temporal response as the location of the laser excitation spot on the waveguide is varied. These observations can be understood in terms of exciton- polarization propagation in the waveguides. The speed of generated polaritons with energy corresponding to the well transitions in the waveguides was determined from the time delay of the temporal response to be approximately (1.26+/- 0.16 x 107 m/sec. The optical loss in the waveguides was determined to be about 5-8 cm-1 for different excitation intensities. The implications of these results to waveguiding in optical devices based on the III- nitride semiconductors are discussed.

Paper Details

Date Published: 11 June 2002
PDF: 8 pages
Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); doi: 10.1117/12.470430
Show Author Affiliations
Tom Nelson Oder, Kansas State Univ. (United States)
Jing Li, Kansas State Univ. (United States)
Jing Yu Lin, Kansas State Univ. (United States)
Hongxing Jiang, Kansas State Univ. (United States)

Published in SPIE Proceedings Vol. 4643:
Ultrafast Phenomena in Semiconductors VI
Kong-Thon F. Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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