Abstract
In this research work, we fabricated SPA solar cell by combining a-Si:H and poly-Si thin films having different band gaps for absorber layers to get the full photovoltaic potential of both. Inductively coupled plasma enhanced chemical vapor deposition system with low inductance antenna design (LIA-ICPCVD) was used to obtain doped and undoped hydrogenated amorphous as well as poly silicon thin films. Amorphous silicon films of 1.75eV band gap and poly-Si films of 1.285eV band gap with a crystalline volume fraction of 82.63% were obtained in this study. Conductivity of n-doped poly-Si and p-doped a-Si:H were 1.916 Ω-1cm-1 and 0.552 Ω-1cm-1respectively. After optimizing the thickness of each layer in this solar structure, we tried to get the required band gap for poly-Si layer by optimizing the process pressure. An efficiency of 1.595% was reached in this case and also QE measurement showed two peaks in shorter as well as in the longer wavelength spectrum. After annealing in hydrogen, efficiency of this cell increased to 1.678%. After replacing the p-doped amorphous Si layer and amorphous absorber layer with larger energy band gap, the efficiency of the cell increased to 3.24% and after annealing it showed an efficiency of 3.56 %.Stability of SPA cell was tested and found that short circuit current and open circuit voltage remained unchanged after 50 days. Key word: thin film solar cell、poly-Si and a-Si:H absorber layers、full spectral absorption