Modeling of N-i-P Vs. P-i-N InGaN solar cells with ultrathin GaN interlayers for improved performance

Abstract

P-i-N structure solar cells often provide improved performance over N-i-P devices because acceptors are easier to activate when the p-type layer is close to the surface. However, for strained InGaN solar cells on GaN, the polarization-induced electric field creates a barrier for photocurrent that impedes device performance. In this paper we show that for Ga-face growth, N-i-P structures can provide improved performance because the electric field from the junction is parallel to that formed from polarization induced sheet charges. Thus the fields complement each other to assist in creating photocurrent in N-i-P devices. Additionally we simulate an N-i-P cell using the recently demonstrated insertion of ultra-thin GaN interlayers to achieve thick strained layers with high material quality.