High Throughput Boron Emitter Formation from Pre-deposited APCVD BSG Layers for TOPCon Solar Cells

This work presents an alternative boron diffusion approach for tunnel oxide passivated contact TOPCon solar cells enabling a highly increased throughput compared to the typically used BBr3 diffusion. We use APCVD BSG layers as the boron dopant source and combine them with a subsequent thermal anneal for dopant drive-in in a quartz tube furnace. Here, we use either a conventional single slot quartz boat configuration, or, for highly increased throughput, a vertical wafer stack configuration with the wafer surfaces in direct contact to each other. We investigate the emitter dark saturation current densities j0e as well as the energy conversion efficiency of TOPCon solar cells fabricated for each configuration and compare the results to those of a BBr3 reference process.