Improved photovoltaic properties of amorphous silicon thin-film solar cells with an un-doped silicon oxide layer

This paper proposes the use of undoped hydrogenated microcrystalline silicon oxide (mu c-SiOx:H) deposited on the n-mu c-Si:H layer of amorphous silicon single-junction superstrate configuration thin-film solar cells produced through 40 MHz very high frequency plasma-enhanced chemical vapor deposition. Raman spectroscopy and optoelectronic analyses of the undoped mu c-SiOx:H thin film revealed that adding a small amount of oxygen into a network results in a low optical absorption, wide band gap, high optical band gap E-04, high refractive index, reasonable conductivity, and crystalline volume fraction, which are advantageous properties in solar cells. Compared with a standard cell, the current density-voltage (J-V) characteristics of the cell with an undoped mu c-SiOx:H/n-mu c-Si:H structure showed an enhancement in short-circuit current density J(sc) from 1332 to 13.60 mA/cm(2), and in conversion efficiency from 8.53% to 8.61%. The increased J(sc) mechanism can be attributed to an improved light-trapping capability in the long wavelength range between 510 and 660 nm, as demonstrated by the external quantum efficiency. (C) 2014 Elsevier Ltd. All rights reserved.