Control of epitaxial growth at a-Si:H/c-Si heterointerface by the working pressure in PECVD

Abstract

The epitaxial-Si (epi-Si) growth on the crystalline Si (c-Si) wafer could be tailored by the working pressure in plasmaenhanced chemical vapor deposition (PECVD). It has been systematically confirmed that the epitaxial growth at the hydrogenated amorphous silicon (a-Si:H)/c-Si interface is suppressed at high pressure (hp) and occurs at low pressure (lp). The hp a-Si:H, as a purely amorphous layer, is incorporated in the lp-epi-Si/c-Si interface. We find that: (i) the epitaxial growth can also occur at a-Si:H coated c-Si wafer as long as this amorphous layer is thin enough; (ii) with the increase of the inserted hp layer thickness, lp epi-Si at the interface is suppressed, and the fraction of a-Si:H in the thin films increases and that of c-Si decreases, corresponding to the increasing minority carrier lifetime of the sample. Not only the epitaxial results, but also the quality of the thin films at hp also surpasses that at lp, leading to the longer minority carrier lifetime of the hp sample than the lp one although they have the same amorphous phase.

Promise of commercialization: Carbon materials for low-cost perovskite solar cells

“…In order to convert solar energy into electric energy which can be directly used by modern society, various kinds of solar cells were designed. Solar cell technologies are grouped into three generations by Martin Green, [1] the first generation usually refers to mono-crystalline silicon and poly-crystalline silicon solar cells, [2][3][4] the second generation is the family of thin film solar cells (such as cadmium sulphide, cadmium telluride, copper indium diselenide, and amorphous silicon), and the third generation includes polymer solar cell (PSC), dye-sensitized solar cell (DSSC), quantum dot solar cell (QDSC), and so on, which utilize new materials and nanotechnology. So far, the family of silicon-based solar cells dominates the world's photovoltaic market, but they suffer from drawbacks such as high manufacturing cost, high energy-consumption processes, and severe environmental pollution during the production process.…”