Numerical simulation and optimization of Si/BaSi2 heterojunction and BaSi2 homojunction solar cells

Abstract

High light absorption material BaSi2 based heterojunction and homojunctin solar cells were simulated with the program AMPS (analysis of microelectronic and photonic structures)-1D in order to thoroughly understand the mechanism for further improvement in conversion efficiency. Simulation results demonstrated that p+-Si/n-BaSi2 heterojunction solar cells exhibited superior photoelectric performances as compared with n+-Si/p-BaSi2 solar cells. A high conversion efficiency up to of 22.7% were achieved by p+-Si (100 nm, NA = 5 × 1019 cm−3)/n-BaSi2 (2000 nm, ND = 1 × 1018 cm−3) heterojunction solar cell. For BaSi2/BaSi2 homojunction solar cells, the window layer should be designed as thin with large scale uniformity and high quality in achieving high efficiency. Both n+-BaSi2 (5 nm, ND = 5 × 1019 cm−3)/p-BaSi2 (2000 nm, NA = 1 × 1017 cm−3) homojunction and p+-BaSi2 (5 nm, NA = 5 × 1019 cm−3)/n-BaSi2 (2000 nm, ND = 1 × 1017 cm−3) homojunction solar cells gave out a high conversion efficiency of 22.5%. Both donor-like defects in p-BaSi2 and acceptor like defects in n-BaSi2 light absorption layers were identified to significantly influence the solar cell performance that all parameters deteriorated severely under high bulk defect density. Moreover, p+-Si/n-BaSi2 solar cell was more sensitive to high level interface trap defects on account of the sharp dropping down of Eff under high interface trap density over 5 × 1012 cm−2. This work provided insight essential guidance for device design and optimization in achieving high efficiency silicide solar cell with low cost.