Ultrathin GaAs solar cells with a high surface roughness GaP layer for light‐trapping application
D. van der Woude, Luc M. van der Krabben, G.J. Bauhuis, Maarten van Eerden, Jae Jin Kim, P. Mulder, Joost Smits, Elias Vlieg, J.J. Schermer
Abstract
Abstract By reducing the thickness of the absorber layers, ultrathin GaAs solar cells can be fabricated in a more cost‐effective manner using less source material and shorter deposition times. In this work, ultrathin GaAs solar cells are presented with a diffuse scattering layer based on wide bandgap GaP grown directly on the device layers of the cells with MOCVD. The roughness and surface morphology are quantified using atomic force microscopy and the resulting diffuse scattering capability is assessed using wavelength‐dependent reflectance measurements. Ohmic rear contacts are made using contact points etched through the GaP layer, for which an etching procedure using I 2 :KI was developed and optimized. The performance of the GaP textured ultrathin GaAs cells are compared with equivalent planar cells using current density‐voltage measurements and external quantum efficiency measurements, where the GaP textured cells demonstrate an increase of 6.7% in the short‐circuit current density ( J SC ), which was found to be as high as 21.9 mA·cm −2 as a result of increased photon absorption by light‐trapping.