Infrared response of lateral pin structure of high titanium doping Silicon-On-Insulator material

Intermediate band (IB) solar cell is a promising third-generation solar cell to achieve very high efficiency above Shockley-Queisser limit. One of the promising ways to IB material is to introduce heavily doped deep level impurities in conventional semiconductors. High-doped Ti with concentration of 10²⁰-10²¹/cm³ in the p-type top Si layer of Silicon-On-Insulator (SOI) substrate is obtained by ion implantation and rapid thermal annealing (RTA). Secondary ion mass spectrometry measurements confirm that Ti concentration exceeds the theoretical Mott limit, the mainly requirement to form impurity intermediate band. Increased absorption is observed in the infrared region by Fourier Transform Infrared Spectroscopy (FTIR) technology. Using lateral p-i-n structure, obvious infrared response in the range of 1100-2000nm is achieved in heavily Ti-doped SOI substrate, suggesting that the improvement in IR photoresponse is a result of increased absorption in the IR. The experimental results indicate that the heavily Ti-implanted Si can be used as a potential kind of intermediate-band photovoltaic material to utilize infrared photons of solar spectrum.