摘要
We demonstrate an all optical approach that can surprisingly offer the possibility of yielding much more information than one would expect,pertinent to the carrier recombination dynamics via both radiative and nonradiative processes when only one dominant deep defect level is present in a semiconductor material.By applying a band-defect state coupling model that explicitly treats the inter-band radiative recombination and Shockley-Read-Hall(SRH)recombination via the deep defect states on an equal footing for any defect center occupation fraction,and analyzing photoluminescence(PL)as a function of excitation density over a wide range of the excitation density(e.g.,5-6 orders in magnitude),in conjunction with Raman measurements of the LO-phonon plasmon(LOPP)coupled mode,nearly all of the key parameters relevant to the recombination processes can be obtained.They include internal quantum efficiency(IQE),minority and majority carrier density,inter-band radiative recombination rate(Wr),minority carrier nonradiative recombination rate(Wnr),defect center occupation fraction(f)),defect center density(Nt),and minority and majority carrier capture cross-sections(σt andσtM).While some of this information is thought to be obtainable optically,such as IQE and the Wr/Wnr ratio,most of the other parameters are generally considered to be attainable only through electrical techniques,such as current-voltage(Ⅰ-Ⅴ)characteristics and deep level transient spectroscopy(DLTS).Following a procedure developed herein,this approach has been successfully applied to three GaAs double-heterostructures that exhibit two distinctly different nonradiative recombination characteristics.The method greatly enhances the usefulness of the simple PL technique to an unprecedented level,facilitating comprehensive material and device characterization without the need for any device processing.
基金
This work was authored in part by the National Renewable Energy Laboratory,operated by Alliance for Sustainable Energy,LLC,for the U.S.Department of Energy(DOE)under Contract No.DE-AC36-08GO28308,Funding provided by the U.S.Department of Energy Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Office
F.Z.also acknowledges Guangdong Basic and Applied Basic Research Foundation(2021A1515110170).