Poly-Si/Siox/C-Si Passivating Contact With 738mv Implied Open Circuit Voltage Fabricated By Hot-Wire Chemical Vapor Deposition

Hot-wire chemical vapor deposition (HWCVD) was utilized to develop a fast and high quality a-Si:H thin film fabrication method for poly-Si/SiOx carrier selective passivating contacts targeting at n-type passivated emitter rear totally diffused crystalline silicon solar cells. The microstructure and hydrogen content of the a-Si: H thin films were analyzed by Fourier-transform infrared spectroscopy in order to understand the influence of film properties on passivation and conductivity. Dense layers were found to be beneficial for good passivation. On the other hand, blistering appeared as a-Si: H layers became more and more dense. However, by adjusting the SiH4 flow rate and the substrate heater temperature, blistering of a-Si: H could be avoided. A suitable process window was found and firing-stable implied open circuit voltage (iV(oc)) of up to 738mV was achieved. In addition to high iV(oc), a low contact resistivity of 0.034 Omega cm(2) was also achieved. The deposition rate of the a-Si: H layers was 7 angstrom/s by using HWCVD, which is one order of magnitude higher than the deposition rate reported using other deposition methods. Published under license by AIP Publishing.