Analysis of local boron dopings formed with LCP

The analysis of local boron dopings formed with an alkaline aqueous boron solution as doping medium for Laser Chemical Processing (LCP) is presented. Successful local p-type boron doping using the LCP process is demonstrated for the first time. The first experiments show the ability of the used boron solution to create a surface boron doping density of 1×1020 cm-3 and a doping depth of about 1 µm. The variation of the doping depth with the pulse energy lead to LCP boron doped lines with a sheet resistance of 25 ohm/sq. to 230 ohm/sq. Furthermore, the recombination properties of local LCP boron dots were analyzed. The first experiments of dot shaped LCP boron dopings as local back surface fields for high efficiency silicon solar cell structures showed the demand for higher pulse energies or an optimized contact design to increase the effective contacting area and to reduce series resistance losses at the contacts.