Fe和Cu杂质对Si材料响应特性影响的对比分析

Comparison of the effects of Fe and Cu impurities on the response characteristics of silicon

摘要:

针对Si中容易混入Fe杂质和Cu杂质的问题,根据第一性原理和光电响应理论,建立了两种杂质混入下的Si模型,比较了不同间隙位置的杂质原子对Si材料的能级结构及响应特性的影响。结果表明:两种杂质的混入均会导致Si材料能级结构发生变化,从而使Si材料能够出现带外响应,且使得光敏单元的饱和阈值降低。具体而言,Fe杂质在四面体间隙位时,Si材料能级结构会受到明显影响,其带隙减小至0.013 eV,从而在约1 560 nm处出现带外吸收峰。Cu杂质则是在六边形间隙位时对Si材料的影响明显,使材料带隙消失,且在约1 700 nm处出现带外吸收峰。这两种情况下Si 基光敏单元的饱和阈值下降也最为明显,当1 550 nm 激光辐照时,饱和阈值分别为0.001 65 W·cm-2和0.002 54 W·cm-2。分析结果可为光电器件的应用和研制提供参考。

Abstract:

Considering that Si-based materials are easily mixed with Fe impurities and Cu impurities during the fabrication process,we establish Si models with two different impurities according to the first-principles and photoelectric response theory.The effects of impurity atoms at different interstitial sites on the energy band structure and response characteristics of Si are further compared.Results show that the mixing of the two impurities can lead to changes in the energy band structure of the silicon material,resulting in an out-of-band response and a decrease in the saturation threshold of the photosensitive unit.Specifically,when the Fe impurity occupies the tetrahedral interstitial site,the energy band structure of silicon is significantly affected,and its band gap is reduced to 0.013 eV,resulting in an out-of-band absorption peak at about 1 560 nm.The Cu impurity has an obvious effect on silicon material at the hexagonal inter-stitial site,so that the band gap disappears,and an out-of-band absorption peak appears at about 1 700 nm.In these two cases,the saturation threshold of the silicon- based photosensitive unit also decreases most significantly.When irradiated by a 1 550 nm laser,the saturation thresholds are 0.001 65 W·cm-2 and 0.002 54 W·cm-2,respectively.The analysis results provide reference for the application and development of optoelectronic devices.