Effect of hydrogen defects on nanocrystallite layers of Si solar cells by hydrogen implantation

The Si solar cells were irradiated with high energy hydrogen ions of 10, 30, 60 and 120?keV at the dose rate of 10¹⁷ H⁺ ions (proton)/cm². The structural, optical and electrical properties of the implanted samples and fabricated cells were studied. The implantation induced defects bringing structural changes before and after annealing was evidenced by the transmission electron microscopy. The Raman spectrum showed a change of crystalline to amorphous state at 480?cm^?1 when the sample was implanted by hydrogen ion of 30?keV energy. Formation of nanocrystallite layers were observed after annealing. The electroluminescence images showed that hydrogen-related defect centers were involved in the emission mechanism. The photoluminescence emission from the implanted cells was attributed to nanocrystallite layers. From current–voltage measurements, the conversion efficiencies of implanted Si solar cells were found lower than the un-implanted reference cell. The ion implantation did not passivate the defects rather acted as recombination centers.