p- and n-type microcrystalline silicon oxide (μc-SiO_x:H) for applications in thin film silicon tandem solar cells

We report on the development and application of p- and n-type hydrogenated microcrystalline silicon oxide (μcSiO_x:H) alloys in tandem thin film silicon solar cells. Our results show that the optical, electrical, and structural properties of μc-SiO_x:H can be conveniently tuned over a wide range to fulfil the requirements for solar cell applications. We have shown that adding of PH₃ gas during deposition tends to increase crystallinity of μc-SiO_x:H layers, while additional trimethylboron (TMB) tends to suppress crystalline growth. When applied in tandem solar cells, both p- and n-type μc-SiO_x:H lead to a remarkable increase in the top cell current. Taking advantage of low refractive index and high optical band gap of μc-SiO_x:H allows the achievement of high efficiencies of 13.1% (initial) and 11.8% (stabilized). (author)