Analyses of Polymer Passivation on the Surface Reflectivity of GaAs/AlGaAs Solar Cell

Abstract

A traditional III-V GaAs/AlGaAs based semiconductor solar cell heterojunction structure, i.e. n-GaAs/n-AlGaAs/n-GaAs/i-GaAs/p-GaAs is used in this study to investigate the surface polymer passivation on this kind of solar cell. For GaAs/AlGaAs solar cell, the top n-GaAs/n-AlGaAs structure is responsible for the selective etching stop layer. The selective etched surface barriers associated with polymer gratings with different aspect ratios, i.e. grating period (gp) to depth (d), are produced on solar cell surface by using the photolithography and Micro Electro Mechanical Systems (MEMS) techniques. A reflective-type diffraction optical grating is fabricated on the surface of the solar cell to redirect the incident light reflected from the solar cell back onto the solar cell surface. The experimental results show that the addition of the surface optical gratings reduce the light reflectivity value as high as 25%. From inspection of surface reflectivity , the average reflectivity is found to be decreased from 12.1% down to 7.9 %.