Dependence of radiative and nonradiative recombination on carrier density and Al content in thick AlGaN epilayers

• Published in: Journal of physics. D, Applied physics Vol. 49; no. 14; pp. 145110 - 145115
• Main Authors: Podlipskas, Aleksiej nas, R, Kadys, A, Mickevi ius, J, Jurkevi ius, J, Tamulaitis, G, Shur, M, Shatalov, M, Yang, J, Gaska, R
• Format: Journal Article
• Language: English
• Published: IOP Publishing 13.04.2016
• Subjects: AlGaN epilayers; Aluminum gallium nitrides; Carrier density; Carrier recombination; Carriers; Dynamic tests; Dynamics; efficiency droop; internal quantum efficiency; light induced transient gratings; Mathematical models; radiative recombination; Recombination coefficient
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/49/14/145110

Dynamics of radiative and nonradiative recombination of non-equilibrium carriers is investigated in thick AlGaN epitaxial layers with Al content ranging from 0.11 to 0.71. The internal quantum efficiency (IQE) in the epilayers was obtained using two approaches: either estimated from PL measurements or calculated using the recombination coefficients of a simple ABC model, retrieved by fitting the kinetics of light induced transient gratings (LITG). At photoexcited carrier densities below ~1019 cm−3, both approaches provided similar IQE values indicating that the simple ABC model is applicable to analyze carrier recombination at such carrier densities. The increase in IQE at higher carrier densities slowed down for the values extracted from PL considerably faster than for those obtained from LITG transients. This discrepancy is explained in terms of the mixed nature of the rate coefficient B caused by the onset of the density-activated nonradiative recombination at high carrier densities.