纳米金属粒子梯度掺杂的硅基近红外吸收增强结构

Silicon based near-infrared absorption enhancement structure with gradient doping of nano metal particles

硅基光电子与CMOS工艺兼容,借助成熟的微电子加工工艺平台可以实现大规模批量生产,具有低成本、高集成度、高可靠性的优势。其中,硅基半导体探测器是目前应用最为广泛的可见光波段探测设备,将其工作频段拓展到近红外波段具有重要意义。由于硅的禁带宽度,硅基材料在近红外波段电磁波吸收存在明显限制,硅基探测器在近红外波段的应用受到挑战。根据纳米金属粒子发生局域表面等离子共振时产生的近场增强效应,提出了一种纳米金属粒子梯度掺杂的硅基结构。通过应用等效介质理论,模拟了复合硅基结构在可见光与近红外波段的吸收特性。结果表明:该结构在近红外波段具有电磁波吸收提升效果,并且当选择纳米金粒子梯度递增掺杂时,可以在610~1 450 nm波段提升吸收性能,最高提升可达到10.7 dB。所提出的结构可以有效增强硅基材料在近红外波段的吸收效率,研究结果为硅基半导体探测器在近红外波段的应用提供了重要参考。

Objective Silicon based optoelectronics are compatible with CMOS technology,and with the help of mature microelectronic processing platforms,large-scale mass production can be achieved.It has the advantages of low cost,high integration,and high reliability.Among them,the application of silicon based semiconductor detectors in the visible light band has become more mature.However,the commonly used semiconductor materials for near-infrared band detectors have drawbacks such as difficulties in compatibility with existing CMOS processes and high prices.Therefore,expanding the operating frequency range of silicon based semiconductor detectors to the near-infrared band is of great significance.Due to the bandgap width of silicon,there are significant limitations in the absorption of electromagnetic waves by silicon based materials in the near-infrared band,posing serious challenges for the application of silicon based detectors in the near-infrared band.Methods In order to break through the bandgap width limitation of silicon and improve the absorption performance of silicon materials in the near-infrared band,a silicon based structure based on gradient doping of nanometallic particles was proposed,based on the near-field enhancement effect generated by local surface plasmon resonance of nanometallic particles.The slow change in doping concentration can effectively solve the severe change in reflectivity caused by refractive index mutation.By applying the Maxwell Garnett equivalent medium theory,the absorption characteristics of composite silicon based structures in the visible and near-infrared bands were simulated,and the effects of two doping concentration changes and two doping metals on the absorption enhancement effect of silicon based materials were compared.Results and Discussions The results indicate that the structure has a significant improvement in electromagnetic wave absorption in the near-infrared band.When the doped metal is silver,both decreasing and increasing doping can bring absorption improvement in the 640-1080 nm wavelength range.However,increasing doping can avoid the drastic change in reflectivity caused by refractive index mutations,and its effect is significantly better than decreasing doping(Fig.6).When comparing the effects of different metals,the absorption enhancement band brought by the doping of gold nanoparticles is wider than that of silver nanoparticles.So when choosing gradient increasing doping of gold nanoparticles,the effect is optimal,and the absorption performance can be improved in the 610-1450 nm wavelength range,with a maximum improvement of 10.7 dB(Fig.7).Conclusions A silicon based structure that can break through the bandgap width limitation of silicon was proposed,near-infrared absorption enhancement was achieved,and the absorption enhancement effect under different conditions was simulated and analyzed.The proposed structure can effectively enhance the absorption efficiency of silicon based materials in the near-infrared band,which helps to improve the performance of silicon based devices.And by comparing different doping methods and metal selection,it is concluded that gradient increasing doping of gold nanoparticles is the optimal choice.The research results of this article provide important references for the application of silicon based semiconductor detectors in the near-infrared band.