Design and Analysis of Light Trapping in Thin Film GaAs Solar Cells Using 2-D Photonic Crystal Structures at Front Surface

Abstract

This paper proposes a design using a 2-D photonic crystal (PhC) structure-based thin film heterojunction GaAs solar cell with a periodic pattern extending from top transparent conducting oxide to inside the p-AlGaAs window layer placed just above the active layer of GaAs material. This paper presents the theoretical optical study and optimization of all the required parameters. This paper presents the optical optimization study for thin active layer cell in the generalized manner for 50-nm active layer, and then the performance of the proposed structure is compared with Lambertian limits and the planar cell, taken as reference. It has been predicted that these wavelength scale periodic structures greatly enhances the performance of the cell. The improvement in the performance is basically accounted for the better diffraction capability, impedance matching, trapping of high wavelength photons, and reduction in reflections from the top due to the PhC structure. The parameters have been optimized and calculated by means of rigorous coupled wave analysis.