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

Abstract This paper proposes the use of undoped hydrogenated microcrystalline silicon oxide (μc-SiO x :H) deposited on the n-μc-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 μc-SiO x :H thin film revealed that adding a small amount of oxygen into a μc-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 μc-SiO x :H/n-μc-Si:H structure showed an enhancement in short-circuit current density J sc from 13.32 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.