OPTICAL CONFINEMENT EFFECT FOR BELOW 5 MU-M THIN-FILM POLY-SI SOLAR-CELL ON GLASS SUBSTRATE

The optical confinement effect of a thin film poly-Si solar cell on a glass substrate fabricated by plasma chemical vapor deposition (CVD) a t low temperature has been investigated for a cell thickness of less t han 5 mu m. The structure of the cell is glass/back reflector/n-i-p po ly-Si/ITO/Ag grid. The cell with a thickness of 3.5 mu m demonstrated an intrinsic efficiency of 9.8%, as independently confirmed by Japan Q uality Assurance. The cell is well characterized by the structure of n aturally surface texture and enhanced absorption with a back reflector (STAR). The optical confinement effect of the cell with STAR structur e explains both the excellent high short circuit current density of ab ove 27 mA/cm(2) for the 4.7 mu m thick cell and the markedly high quan tum efficiency at long wavelength as determined through PClD analysis.