Experimental measurement of lateral transport in the inversion layer of silicon heterojunction solar cells

We performed two experiments to measure lateral flow of photoexcited charge carriers near the heterointerface in silicon heterojunction (SHJ) solar cells. Using light beam methods, we probed current extraction differences between areas of varying intrinsic layer thickness and the effective cross section of junction defects. Both measurements demonstrated a strong bias voltage dependence of lateral transport and transport lengths of tens to hundreds of microns as bias approached operating voltages. Lateral carrier flow near the heterointerface is proposed as one of the reasons that SHJ solar cells are extremely sensitive to interfacial defects.