The internal quantum efficiency (IQE) in a GaN epilayer is quantified using transient lens (TL) spectroscopy and numerical simulations. TL spectroscopy can optically detect temperature and carrier changes induced in a photo-pumped GaN layer, and the observed temperature change is closely associated with non-radiative recombination processes that create heat. Then numerically solving diffusion equations, which represent the diffusion processes of the photo-generated heat and carriers, provide the spatiotemporal distributions. These distributions are subsequently converted into the refractive index distributions, which act as transient convex or concave lenses. Finally, ray-tracing simulations predict the TL signals. Comparing the experimentally obtained and simulated TL signals quantifies the generated heat and the IQE without the often-adopted assumption that non-radiative recombination processes are negligible at low temperatures.
Quantification of the internal quantum efficiency in GaN via analysis of the heat generated by non-radiative recombination processes
Yoichi Kawakami, Kohei Inoue, Akio Kaneta, Koichi Okamoto, Mitsuru Funato; Quantification of the internal quantum efficiency in GaN via analysis of the heat generated by non-radiative recombination processes. J. Appl. Phys. 14 March 2015; 117 (10): 105702. https://doi.org/10.1063/1.4914413
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