Preparation of B-doped Si quantum dots embedded in SiN${}_x$ films for Si quantum dot solar cells

Silicon quantum dots (Si-QDs) embedded B-doped SiN${}_x$ films were fabricated by magnetron co-sputtering. The effects of B content on the structural, optical and electrical properties of the films were studied. The study found that the amount of B dopant has no significant effect on the crystallization characteristics of the films. B atoms may be doped in the Si-QDs or exist in the silicon nitride or the interface between Si-QDs and the matrix. PL intensity increases with increasing B content, but increases at first and then decreases. The conductivity as a function of the dopant concentration increases at first from a value of 2.71 × 10${}^{-4}$ S/cm to 5.83 × 10${}^{-2}$ S/cm until 0.9 at.% and then decreases. By employing B-doped Si-QDs films, Si-QDs/c-Si heterojunction solar cells were fabricated and the effect of B doping concentration on the photovoltaic properties was studied. It was found that, with the increase of B doping amount, the photovoltaic performance is improved, when the B doping amount is 0.9 at.%, the efficiency reaches the highest value of 4.26%.