Inkjet-Printed Diffusion Sources

Abstract

This paper presents an up-scalable solution for the formation of doped areas based on inkjet printing of boron and phosphorous doping inks. The influence of the thickness of the inkjet-printed doping source layers and the diffusion temperature on the sheet resistance is evaluated. In addition, the doping profiles are measured. For a diffusion temperature of 950 °C a sheet resistance of 50 Ω/sq is achieved with the boron ink. At the same temperature a sheet resistance of 18 Ω/sq is achieved with the boron ink. The process is then for the first time applied for the fabrication of back-contact back-junction solar cells with inkjet-printed p+-emitter. The best solar cell features an efficiency of = 20.6 %. To date, these are the best solar cells with an inkjet-printed doping source. Lifetime samples that are processed in parallel exhibit an emitter saturation current density below 90 fA/cm2.