OPTIMIZATION OF A-SIC: HASBUFFER LAYER FOR EFFICIENCY ENHANCEMENT OF AMORPHOUS SILICON SOLAR CELLS

T.K.Subramanyam, Thulasi, Ankita Bengani, Bharath Shivkumar, R.Suresh

Abstract: Thin film single junction hydrogenated amorphous silicon (a-Si:H) solar cells have been fabricated using RF-Plasma Enhanced Chemical Vapor Deposition method. The p-,i-, and n-layers have been optimized individually for achieving cell efficiency of 5.11 %(Voc=0.84 V, Jsc=10.13 mA/cm2, and FF=0.59). In this study an effort has been made to optimize and incorporate hydrogenated amorphous silicon carbide (a-SiC:H) layer as a buffer layer between the doped a-Si:H forming the emitter (p-layer) and the absorber layer (i-layer) to enhance the cell efficiency further.The buffer layer has been studied for electrical, optical, structural properties and layer thickness by varying the process parameters such as CH4, SiH4 and H2 gas concentrations. The optimized buffer layer was about 12 nm thick with an optical band gap of 1.88 eV. Insertion of this film between the p- and i- layers resulted in an increased power conversion efficiency of 5.88% and Jsc=11.0mA, compared to the conventional cells. The observed improvement is related mainly to minimum absorption loss and capability of driving out the photo generated carriers with minimum recombination losses, with transportation of carriers to the outer circuit with minimum electrical resistance.

Keywords: a-Si:H solar cell, a:SiC:H,Buffer Layer, PECVD.

DOI: https://doi.org/10.15623/ijret.2016.0527012