Synthesis of Phosphorus Solution for n⁺ Si Selective Emitter Solar Cell by Spin on Doping

School of Electrical Engineering, Suranaree University of Technology, Nakhon Ratchasima, Thailand

^* Corresponding author: thipwan@g.sut.ac.th

Abstract

A strong requirement in manufacturing of high-efficiency solar cells is its cost reduction. One approach of aim is to merge several steps of n⁺ Si selective emitter processing into one step without degrading the performance of solar cells. By varying the doping level in the selective area, intrinsic fields can be built into solar cells with potential benefits long recognized. In this paper, the spin-on doping (SOD) method was used for the purpose of important tasks, different phosphorus diffusion to form n+ Si selective area consisting of the lightly and heavily doping emitter areas with 35 Ω/sheet and 121 Ω/sheet. The main solution containing different concentrations of phosphorus doped-SOD source was synthesized in this work. The sheet-resistance dependence of n-Si emitter layers on the concentration of phosphorus acid in the SOD solution was studied in term of the volume ration of TEOS: H₃PO₄, as well as the thermal diffusion temperature. The suitable condition for forming n⁺ Si selective emitters in one process step is 1000°C diffusion temperature for 30 minutes with the complementary SOD volume ratio of 4:1 and 2:1. SOD solution can be patterned by a screen printing or an inkjet printing.