Minority Carrier Collection Enhancement Model for the Deeply Grooved Solar Cell

Abstract Although many solar cell designs for low‐concentration linear focus applications have utilized the ‘prismatic cover’ for reducing gridline shadings the deeply grooved solar cell represents an effort to integrate the prismatic cover into the basic device design for performance enhancement. The design is based on deep (140‐μm) grooves in 〈100〉 orientation silicon, with an active‐area silicon ‘ridge’ between gridlines. The silicon ridge should improve minority carrier collection efficiency as compared to planar designs, due to the two‐dimensional nature of current collection, and the placement of light on the ridge by the focus of the prismatic cover. This article describes the enhancement mechanism by using a model based on the superposition of two specific solutions of the transport equation. The enhancement model is in support of the approximation that for one‐dimensional numerical modeling, the ‘effective’ diffusion length is the sum of the bulk silicon diffusion length and the height of the ridge. Data collected from prototype solar cells provide some experimental support for the model, but difficulty in fabrication using typical semiconductor processing has limited full realization of the structure.