Contribution of dislocations to carrier recombination and transport in highly excited ELO and HYPE GaN layers
2006 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, Vol. 243, no 7, 1426-1430 p.Article in journal (Refereed) Published
Nonequilibrium carrier dynamics has been investigated in ELO and HYPE grown GaN layers in a wide temperature and excitation range by using the time-resolved picosecond FWM technique. Carrier lifetime in the samples at 300 K increased up to 2.8-5.1 ns in accordance with the decreasing threading dislocation density from 4 x 10(7) cm(-2) (ELO) to mid 106 cm(-2) in HYPE layers. At T < 100 K, the hyperbolic shape of FWM kinetics indicated carrier density dependent radiative lifetimes, which gradually decreased at lower temperatures to a few hundreds of ps. The dominance of bimolecular recombination in HVPE layers at 10-40 K was demonstrated by the exposure characteristic of FWM, that has shown a sublinear growth of carrier density with excitation, N proportional to I-1/2. Numerical fitting of the set of FWM kinetics at various T confirmed the temperature dependence of bimolecular recombination coefficient B proportional to T-1/5 and provided its value B = 2 x 10(-11) cm(3)/s at 300 K and 3.2 x 10(-9) cm(3)/s at 9 K. The measured bipolar diffusion coefficients allowed determination of carrier diffusion length of 0.8-1 mu m at 300 K and its dependence on dislocation density and temperature. (c) WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Place, publisher, year, edition, pages
2006. Vol. 243, no 7, 1426-1430 p.
National CategoryEngineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-46012DOI: 10.1002/pssb.200565139OAI: oai:DiVA.org:liu-46012DiVA: diva2:266908