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Proceedings Paper

Ultrafast carrier relaxation in group-III nitride multiple quantum wells
Author(s): Umit Ozgur; Henry O. Everitt; Stacia Keller; Steven P. DenBaars; Lei He; Hadis Morkoc
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Paper Abstract

In this study, stimulated emission (SE) and ultrafast carrier relaxation are explored in InGaN and AlGaN/GaN multiple quantum wells (MQWs). The SE threshold densities (Ith) in InGaN MQWs increase with increasing QW depth. By contrast, no significant variation is observed in AlGaN/GaN MQWs with varying barrier height and growth conditions (Ga-rich and N-rich). Wavelength non-degenerate time-resolved differential transmission (TRDT) measurements reveal that increased non-radiative recombination and fast capture of carriers to the localized states below the SE energy in deeper InGaN MQWs are responsible for the increased Ith. At high excitation densities SE is shown to remove carriers efficiently from the QWs with a time constant of a few picoseconds, causing carriers at higher energies to cascade down and refill these SE-emptied states. The strength and decay times of the SE feature, which are resolved from the spectrally integrated TRDT data, are seen to vary as a function of excitation energy and density. The fast, SE-accelerated decay in AlGaN MQWs occurs more than twice as fast as in InGaN MQWs for similar excitation densities. More importantly, recombination times are an order of magnitude faster in AlGaN MQWs than in InGaN MQWs.

Paper Details

Date Published: 16 June 2004
PDF: 11 pages
Proc. SPIE 5352, Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII, (16 June 2004); doi: 10.1117/12.529426
Show Author Affiliations
Umit Ozgur, Virginia Commonwealth Univ. (United States)
Henry O. Everitt, Duke Univ. (United States)
U.S. Army Research Office (United States)
Stacia Keller, Univ. of California/Santa Barbara (United States)
Steven P. DenBaars, Univ. of California/Santa Barbara (United States)
Lei He, Virginia Commonwealth Univ. (United States)
Hadis Morkoc, Virginia Commonwealth Univ. (United States)

Published in SPIE Proceedings Vol. 5352:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII
Kong-Thon Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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