Calculations of light trapping, responsivity, and internal quantum efficiency of In-doped silicon (n) structure

This research intends to investigate a mathematical model for In-doped silicon (n) structure, and calculate the absorbance of the simulated cell, then study the effect of impurity photovoltaic effect on the responsivity and internal quantum efficiency using the Shockley–Read–Hall model. It is found that the internal flux inside the simulated Lambertian cell could be enhanced as much as 25 times as a result of light trapping. Maximum responsivity and internal quantum efficiency of the simulated cell was obtained at a wavelength around 1 μm and 10¹⁷ cm⁻³ indium concentration. Near infrared response of the simulated cell is improved due to the enhancements of sub-band gap response by indium doping. To compare the mathematical model with the practical results, few samples of In-doped n-type silicon structures have been fabricated using the thermal vacuum resistive technique. Maximum responsivity and maximum internal quantum efficiency are obtained at wavelength 0.9–1 μm and 3.96×10¹⁷ cm⁻³ indium concentration. The results of the simulated and practical cells agree.