Nitrogen plasma treatment of fluorine-doped tin oxide for enhancement of photo-carrier collection in amorphous Si solar cells

Abstract

Nitrogen plasma treatment was performed on fluorine-doped tin oxide (SnO(2):F) front electrodes, and its impact on the performance of pin type amorphous Si (a-Si) solar cells was investigated. Nitrogen plasma treatment reverses the surface band bending of SnO(2):F from accumulation to depletion, thus in turn reversing the band bending of the p type amorphous silicon carbide (p-a-SiC) window layer. The reversal of band bending leads to the collection of carriers generated in p-a-SiC, and quantum efficiency in the short wavelength regime is thereby enhanced. On the other hand, surface depletion of SnO(2):F causes a reduction of the diode built-in voltage and increased series resistance, which could degrade the open circuit voltage (Voc) and fill factor (FF), the degradation of which is strongly affected by the deposition time of p-a-SiC. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3572262]