Light beam induced current mapping applied to the characterization of tandem and polycrystalline GaAs devices

The performance of the light beam induced current mapping for controlling various stages during the fabrication of photovoltaic devices is discussed. Two types of devices are analyzed: a high-efficiency minispectral tandem GaAs solar cell and a low-cost solar cell made from polycrystalline GaAs substrate. In the first type, a buried active junction was electrically imaged at 9 μm below the surface of the device by this nondestructive testing method. In the second case, the repartition of the measured photocurrent can be correlated with the different grains of the analyzed zone, and the contribution of each grain can be analyzed by comparison between short-circuit current mapping and open-circuit voltage mapping