Phys. Rev. B 67, 155308 (2003) [9 pages]Ultrafast carrier relaxation in GaN, In0.05Ga0.95N, and an In0.07Ga0.93N/In0.12Ga0.88N multiple quantum well |
Ümit Özgür and Henry O. Everitt *
Department of Physics, Duke University, Durham, North Carolina 27708
Received 16 September 2002; revised 8 January 2003; published 11 April 2003
Room-temperature, wavelength-nondegenerate ultrafast pump/probe measurements were performed on GaN and InGaN epilayers and an InGaN multiple quantum well (QW) structure. Carrier relaxation dynamics were investigated as a function of excitation wavelength and intensity. Spectrally resolved sub-picosecond relaxation due to carrier redistribution and QW capture was found to depend sensitively on the wavelength of pump excitation. Moreover, for pump intensities above a threshold of 100 μJ/cm2, all samples demonstrated an additional emission feature arising from stimulated emission (SE). SE is evidenced as accelerated relaxation (<10 ps) in the pump-probe data, fundamentally altering the redistribution of carriers. Once SE and carrier redistribution is completed, a slower relaxation of up to 1 ns for GaN and InGaN epilayers, and 660 ps for the multiple QW sample, indicates carrier recombination through spontaneous emission.
©2003 The American Physical Society
URL: http://link.aps.org/abstract/PRB/v67/e155308
DOI: 10.1103/PhysRevB.67.155308
PACS: 78.47.+p, 78.66.Fd, 78.45.+h, 78.67.De
* Email address: everitt@aro.arl.army.mil
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