InP-based evanescently coupled high-responsivity photodiodes with extremely low dark current density integrated diluted waveguide at 1550 nm

In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity (> 1 A/W), high saturation power (> 45 mA) in the static state and extremely low dark current density (0.04 pA/μm²) with 3 dB bandwidth at 13.4 GHz have been achieved.     

Infrared response of the lateral PIN structure of a highly titanium-doped silicon-on-insulator material

The intermediate band (IB) solar cell is a promising third-generation solar cell that could possibly achieve very high efficiency above the Shockley-Queisser limit. One of the promising ways to synthesize IB material is to introduce heavily doped deep level impurities in conventional semiconductors. High-doped Ti with a concentration of 10²⁰ cm^-3-10²¹ cm^-3 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 the Ti concentration exceeds the theoretical Mott limit, the main requirement for the formation of an impurity intermediate band. Increased absorption is observed in the infrared (IR) region by Fourier transform infrared spectroscopy (FTIR) technology. By using a lateral p-i-n structure, an obvious infrared response in a range of 1100 nm-2000 nm is achieved in a heavily Ti-doped SOI substrate, suggesting that the improvement on IR photoresponse is a result of increased absorption in the IR. The experimental results indicate that heavily Ti-implanted Si can be used as a potential kind of intermediate-band photovoltaic material to utilize the infrared photons of the solar spectrum.     

单载流子光电探测器的高速及高饱和功率的研究

利用载流子漂移-扩散模型, 模拟并分析了InGaAs/InP单载流子光电探测器(Uni-traveling-carrier/UTC-PD) 在不同条件下的物理特性及其带宽和饱和特性, 结合器件实验结果分析了影响器件高速和高饱和性能的物理机理. 结论表明在吸收区采用浓度渐变掺杂和增加InP崖层(cliff layer), 可以显著提升器件饱和特性, 高入射功率下吸收区电场崩塌是器件饱和的直接因素, 直径大于20 μm的UTC探测器中RC常数仍是影响带宽的主要因素. 论文指出了优化器件结构、 提升器件性能的有效方法.     

Detailed balance limit efficiency of silicon intermediate band solar cells

The detailed balance method is used to study the potential of the intermediate band solar cell (IBSC), which can improve the efficiency of the Si-based solar cell with a bandgap between 1.1 eV to 1.7 eV. It shows that a crystalline silicon solar cell with an intermediate band located at 0.36 eV below the conduction band or above the valence band can reach a limiting efficiency of 54% at the maximum light concentration, improving greatly than 40.7% of the Shockley—Queisser limit for the single junction Si solar cell. The simulation also shows that the limiting efficiency of the silicon-based solar cell increases as the bandgap increases from 1.1 eV to 1.7 eV, and the amorphous Si solar cell with a bandgap of 1.7 eV exhibits a radiative limiting efficiency of 62.47%, having a better potential.