| dc.description.abstract | Recently, the effects of physical properties on silicon-based solar cells have been extensively researched such as the epitaxial silicon solar cell and hetero-junction solar cell which have been produced at low temperatures, low cost and high efficiency. The high doping concentration of an emitter layer in the epitaxial silicon solar cell can be used to form an ultra-shallow junction to obtain a high short current density. For the hetero-junction solar cell, the absorption in a-Si:H will results the lower short current density than the conventional silicon solar cells. Therefore, we use the materials of a-SiC and germanium in the HIT solar cell to enhance the Jsc. In this thesis, we focus on the electrical performance of structural parameters and two-dimensional device modeling for epitaxial silicon solar cell and hetero-junction solar cell are carried out by using Synopsys Technology Computer Aided Design (TCAD) simulation program.
First, we study the performance an emitter (p+)/ base (n)/ BSF (n+) epitaxial silicon solar cell with various parameters, such as the thickness, the doping concentration, the surface recombination velocity, and the work function. The optimal efficiency of 21.2 % can be achieved with 10 nm/300 μm/50 nm, doping concentration of 1×1021/1.6×1015/1×1021 (cm-3) and, the surface recombination velocity of emitter/base and base/BSF are 102 cm/sec.
Nevertheless, from the results of the cells with different ITO work function to achieve ohmic contact, if ITO contacted with p-doped layer, the ITO work function need to lager than the work function of semiconductor. On the other hand, ITO contacted with n-doped layer, the ITO work function need to smaller than the work function of semiconductor.
Second, we demonstrate an a-SiC (p)/ a-SiC (i)/ c-Si (n)/ a-Si (n+) hetero-junction solar cell. We investigate the effect of the thickness, the doping concentration, density of state, and band gap on the performance of the solar cell. According to the simulation results, the structure of a-SiC/c-Si can improve the Jsc of 1.7 mA/cm2. Then, the Jsc can be improved to 46.23 mA/cm2 by using Si0.09Ge0.91 in the HIT solar cell to absorb infared of sunlight. | en_US |