Solar Energy Materials and Solar Cells, Vol.94, No.9, 1512-1515, 2010
High deposition rate device quality a-Si:H films at low substrate temperature by HWCVD technique
Hot wire chemical vapor deposition (HWCVD) provides a low cost fabrication technology for hyrdogenated amorphous silicon (a-Si:H) based thin film single junction and tandem solar cells. In this paper, we report our results on the high deposition rate device quality a-Si:H films deposited by HWCVD at low substrate temperature. Films have been deposited using tantalum filament with highest deposition rates of 16 angstrom/s and having the desired device quality properties like high photoconductivity gain (sigma(ph)/sigma(dark)). low microstructure factor (as revealed by IR spectroscopy), good short range order parameter and acceptable thickness uniformity over the deposited area. An average photoconductivity gain of approximate to 3 x 10(5) has been obtained for the films deposited at rates similar to 15 angstrom/s and the substrate temperature of 200 degrees C. The p- and n-type films have also been deposited by the HWCVD. Single junction p-i-n solar cells on ASAHi U-type substrates, fabricated using these layers have an efficiency of 5.1% under AM1.5 illumination. Depositing anti-reflection coating on front side, reflection coating before back contact and using textured TCO layer for light trapping would further improve the efficiency of the cell. (C) 2010 Elsevier B.V. All rights reserved.