An all optical approach for comprehensive in-operando analysis of radiative and nonradiative recombination processes - deep level optical spectroscopy

We have developed an all optical approach, combining PL and Raman, that can yield practically all of the quantitative information that is pertinent to the carrier recombination dynamics via both radiative and nonradiative processes when deep defect levels are present, including internal quantum efficiency (IQE), minority and majority carrier density, inter-band radiative recombination rate, minority carrier nonradiative recombination rate, defect center occupation fraction, defect center density, and minority and majority carrier capture cross-sections. While some of this information is thought to be obtainable optically, such as IQE, most of the other parameters are generally considered to be attainable only through electrical techniques, such as I-V characteristics and DLTS. This approach uses a band-defect state coupling model that explicitly treats the inter-band radiative recombination and SRH recombination via deep defect states on an equal footing for any defect center occupation fraction. It has been successfully applied to GaAs double-heterostructures that exhibit distinctly different nonradiative recombination characteristics. The all-optical method facilitates comprehensive material and device characterization without the need for any device processing.