ABSTRACT
We report on the co-diffused bifacial N-type solar cells based on N-type Si wafers using the process of spin on doping (SOD, phosphorous source) and boron tribromide (BBr3) diffusion by atmospheric pressure chemical vapor deposition (APCVD). For bifacial co-diffusion, a phosphorous layer was deposited by SOD on the rear side of N-type Si wafer and a BBr3 as boron dopant source deposited by APCVD. Co-diffusion process was controlled by changing the flowrate of carrier N2 gas and drive-in temperatures. It was found that the fabricated bifacial co-diffused N-type solar cell with 2% H3PO4 doping, the flowrate of N2 carrier gas of 15 slm and drive-in temperature at 930°C exhibited the highest conversion efficiency of 15.8% with high open circuit voltage (V(oc)) of 593 mV. As compared to high H3PO4 concentrations (5% and 9%), the low H3PO4 concentration of SOD showed the higher sheet resistance and decreased in the thickness of N + emitter layer, resulting in the high V(oc), shunt resistance, fill factor and conversion efficiency of solar cells.
