Boron-doping effect on the super-high density Si quantum dot thin films utilizing a gradient Si-rich oxide multilayer structure

Boron (B)-doped gradient Si-rich oxide multilayer (GSRO-ML) structure is utilized to realize super-high density Si quantum dots (QDs) thin films with large carrier tunneling probability by co-sputtering. The B-doping effect on crystalline, optical, electrical and photovoltaic (PV) properties of Si QD thin films is investigated in this study. With increased B-doping concentration, the preserved high crystallinity of Si QDs and the reduced optical bandgap are observed. An optimized doping condition is found for the electrical and PV properties. Further increasing the doping concentration leads to increased inactive B atoms and interfacial over-diffusion. The issue of interfacial over-diffusion can be efficiently improved by inserting lowly B-doped GSRO-ML thin films. Our results show the feasibility and great potential for high efficiency Si-based solar cells integrating Si QDs by properly doped B atoms in GSRO-ML thin film structure.