AVS 61st International Symposium & Exhibition
    Electronic Materials and Processing Thursday Sessions
       Session EM1-ThM

Paper EM1-ThM5
Symmetry-Breaking in Light Trapping Nanostructures on Silicon for Solar Photovoltaics

Thursday, November 13, 2014, 9:20 am, Room 311

Session: Materials for Light Management
Presenter: SangEon Han, University of New Mexico
Authors: S.E. Han, University of New Mexico
S. Ghosh, University of New Mexico
T. Cai, University of New Mexico
B.R. Hoard, University of New Mexico
S.M. Han, University of New Mexico
Correspondent: Click to Email
In thin-film photovoltaics, highly absorptive materials are conventionally used. However, these materials except gallium arsenide have achieved efficiencies that are not comparable to those of thick crystalline silicon (c-Si) photovoltaics and, in some cases, suffer from their toxicity and low supply. A viable solution to these problems would be to use c-Si for thin-film photovoltaics. However, thin c-Si films absorb sunlight weakly because of its indirect band gap, and highly efficient light-trapping should be provided to achieve high efficiency. For thin-film photovoltaics, nanoscale structures are typically involved for light trapping because the film thickness becomes comparable to the wavelength of sun light. While diverse nanostructures have been studied to break the light-trapping limit of geometric optics, known as the Lambertian limit, highly efficient nanostructures that can be easily manufactured have not been demonstrated. We have previously predicted that symmetry-breaking in light-trapping periodic nanostructures on thin films can approach the Lambertian limit very closely. Herein, we will present how the systematic symmetry-lowering increases light-trapping in thin-film photovoltaics. Further, we will demonstrate the experimental realization of such low-symmetry structures using simple wet etching methods on c-Si(100) wafers without any off-cut, tilt angle.