研究期間：10112~10211;Both high efficiency and low cost are common goal and essential to solar power technologies. Therefore, the crystalline silicon solar cells in research and development become a major focus recently in order to replace the existing traditional petrochemical power generation. For the project, a research and development team expertise and practical discipline from National Central University and the Institute of Nuclear Energy will be formed. Silicon-based doping layer with variable crystalline fractions and passivation layers will be fabricated and investigated by electron cyclotron resonance chemical vapor deposition (ECRCVD) system and the other extended chamber equipped to the ECRCVD.. Based on the previous results for our planning within next two years, we will develop new a high efficiency ultra-shallow junction silicon solar cells, the photoelectric conversion efficiency will be expected higher than 19% in the first year, and higher than 22% in the second year. In addition, electrodes in fabrication for the industrial production will be critical to make the new structure of ultra-shallow junction solar cells and to meet the needs of industrial production of commercialization goal. The two-year project is divided into four main categories: (1) We will establish a fabrication platform and develop the core technologies of “High Efficiency Si Crystal Solar Cells with Ultra-Shallow Junction” by ECRCVD. These objectives, combined with the inherent cost reduction of scalable processes, have encouraged the work for new techniques that result in high crystalline growth of silicon thin films at lower thermal budget. And the fabrication processes of the ultra-shallow junction solar cells are totally comparable with the industrial productions of the c-Si solar cells (2) We will apply high quality passivation layer to suppress the defect density between the c-Si and additional interface that reduces the interface defects from between the carrier recombination rate and the reverse bias saturation current. It is the conventional method for raising the open-circuit voltage. The passivation layer makes the interface defect density less than 1011 cm-2. It reduces the recombination rate and the reverse bias saturation currents 100cms-1 and 10-13 Acm-2 respectively and is expected to enhance the open-circuit voltage more than 0.65V. (3) We will fabricate high quality silicon films doped layers with variable (10-100%) crystalline fractions as the emitter layers and the back side field layers. The emitter thickness less than 50 nm can be controlled and formed with a highly doped ultra-shallow junction which can enhance the short-circuit current due to reduction of the absorption coefficient of the ultra-thin doped layers. Furthermore, back side field layer is applied to reinforce the built-in electric field in order to enhance the carrier collection rate and to decrease the internal recombination velocity in the c-Si. These can make the short-circuit current density of the solar cell greater than 40 mA / cm2. (4) We will design new shapes on electrode for the solar cells since electrode designs in production of silicon solar cells have great effects on the conversion efficiency and fill factor. The electrode shape determines the collected current ohmic losses and shadowing losses. By estimating various losses sources, we will design a minimum loss of electrode in shapes and it can achieve high short circuit current and low series resistance. The fill factor over 78% will be expected by optimizing the electrode design.
