Laser damage to copper-doped and undoped silicon solar cells

Abstract

An experimental study has been made of the damage to Cu-doped and undoped silicon solar cells caused by a Q-switched ruby laser (6943 nm). The pulses, of 60 MW cm⁻² power density, produce surface damage and a degradation in the photocurrent of the cells. The surface damage of the undoped cells consists of a melting zone and crack lines. For the Cu-doped cells, however, a characteristic damage pattern consisting of short straight lines parallel to [110] and [112] directions is observed. The degradation rate of the spectral photocurrent of the Cu-doped cells is smaller than that of the undoped cells; and the modified damage constant of the Cu-doped cells is smaller by a factor of 2-3 than that of the undoped cells.