Yujie Fan

Selenium-Doped Silicon-on-Insulator Waveguide Photodetector With Enhanced Sensitivity at 1550 nm

This letter describes the fabrication and characterization of a silicon-on-insulator all silicon rib waveguide photodetector with sensitivity at 1550 nm. Response at the subbandgap wavelength is provided through the introduction of deep levels via Se ion implantation. Se ions were implanted into the waveguide using an ion beam energy of 240 keV at a dose of 3×1015 cm-2. The most efficient device has a responsivity of 25 mA/W at 3 V reverse bias. The fabrication is fully compatible with standard complementary metal-oxide-semiconductor processes.

Deep Energy Levels Formed by Se Implantation in Si

To transfer a photon with a 1.55μm wavelength into an electron in an integrated optoelectronic silicon waveguide detector, selenium-doped silicon with deep energy levels is used. The deep levels in the silicon with implanted selenium are studied. Three levels are observed and their captured cross sections, concentrations and in-depth profiles are measured.

The Effects of Femtosecond Laser Irradiation and Thermal Annealing on the Optoelectronic Properties of Silicon Supersaturated with Sulfur

Electrochemical capacitance-voltage profiling, Raman and absorption spectroscopy measurements are employed to characterize the electronic and optical properties of silicon supersaturated with sulfur above the equilibrium solubility limit. Silicon wafers are ion implanted with 50keV32S+ to a dose of 1 × 1016 ions/cm2 and subsequently irradiated by femtosecond pulses at a fluence of 0.2 J/cm2, followed by thermal annealing at 825 K for 30 min. The spectral response of the photodiode fabricated from the laser-irradiated sample is also investigated. It is found that femtosecond laser irradiation and subsequent thermal annealing can electrically and optically activate the supersaturated sulfur dopant in silicon, as well as reduce the implantation-induced damage in the silicon lattice.

Investigation of the forming process and characteristics of Al-BSF in silicon solar cells

This paper is intended to give insights into the forming process and characteristics of aluminum back surface field (Al-BSF) made by thermal evaporation and conventional thermal processing. It is indicated that Al-BSF formation is the result of the recrystallization of silicon and the dissolved silicon is responsible for the BSF thickness. A sufficient oxygen supply at the early stage of firing process is essential to thicken and strengthen oxide layer to protect the liquid aluminum and silicon during firing. It will be formed Al-BSF/Al-Si eutectic/Al2O3 multilayer structure at the back side of Si solar cells and the X-ray measurement demonstrates that the eutectic layer mainly contains Al3.21Si0.47. The Al-BSF has good electrical properties compared with boron-doped p+-Si by Hall tests. Solar cell with Al-BSF significantly increases long-wavelength response compared with the cells with diffused or ion implanted boron-BSF, and the back surface recombination velocity can be reduced as low as to 200 cm/s for Al-BSF passivation.