Boron-rich layer properties formed by boron spin on dopant diffusion in n-type silicon

Starting with N-type base, a p-type emitter is formed using boron spin on dopant (BSoD) which results in formation of boron rich layer (BRL) on top of the emitter and can be used in selective emitter and FF improvements in solar cells. In this work, the morphologies of BRL for varying thicknesses, depending on the diffusion conditions, have been studied to know their impact on emitter formation. The characterizations show that BRL properties are dependent on its thickness and its boron concentration. BRL has amorphous phase with peak boron concentration over 1021 atoms/cm3, thickness less than 100 nm, refractive indices of 1.4-1.6 and contact resistance 1.0-6.0 mΩ-cm2. The bond properties of the constituent elements of BRL vary depending on the thickness.