Solar cell structures combining amorphous, microcrystalline, and single-crystalline silicon

Single- or multiple-junction solar cells combining hydrogenated amorphous silicon (a-Si:H) and/or microcrystalline silicon (μc-Si) thin films with a single-crystalline silicon (c-Si) or polycrystalline silicon (poly-Si) substrate have potential for high efficiency and long-term stability. The processing temperatures for such cells need not exceed 250°C and, except for the Si substrate, only chemical and physical vapor depositions are used for cell fabrication. The authors study two cell structures: single-junction with the structure of p-type μc-Si/p-type a-Si:H/n-type c-Si and two-junction with the structure of n-i-p a-SiC:H/n⁺-p c-Si. In addition to developing solar cells with more efficient light collection, a potential benefit of the multiple-junction cell research is the development of stable, high-efficiency photoelectrodes with a photovoltage of 1.6 V or higher for direct photoelectrolysis of water for hydrogen production. They use a high-frequency (110 MHz) glow discharge of silane for the depositions of μc-Si and a-Si:H