Evaluation of the junction’s electric field and the ideality factor of GaAs p-n junction solar cells by using photoreflectance spectroscopy

Abstract

We investigated the optical and the electrical properties of GaAs solar cells (SCs) by using photoreflectance (PR) spectroscopy and current-voltage (J-V) measurements. The electric fields (F j ) in p-n junctions were evaluated through an analysis of the Franz-Keldysh oscillations (FKOs) of the PR spectra. From the excitation light intensity (I ex ) dependence of the PR, we found that the photovoltaic effect resulted in a reduction of the F j . The F j was gradually reduced by up to 37% from the dark built-in electric field when the I ex was increased (I ex = 2.3 ∼ 181 mW/cm2). We evaluated the ideality factor (n) of the SC via PR spectroscopy, and the results matched the results of the J-V measurements well. From these results, we demonstrate that the F j and the n of the SCs can be evaluated by using PR spectroscopy.