B,P掺杂β-Si3N4的电子结构和光学性质研究

运用第一性原理方法, 计算了B, P两种元素单掺杂和共掺杂的β -Si₃N₄材料的电子结构和光学性质. 结果表明: B掺杂体系的稳定性更高, 而P掺杂体系的离子性更强; 单掺和共掺杂均窄化带隙, 且共掺在禁带中引入深能级, 使局域态增强; 单掺杂体系介电函数虚部、吸收谱和能量损失谱各峰均发生红移、幅值减小, 而共掺后介电函数虚部主峰出现蓝移、能量损失峰展宽、高能区电子跃迁大大增强, 且控制共掺杂的B, P比例可获得较低的带电缺陷浓度.

Electronic structures and optical properties of boron and phosphorus doped β-Si3N4

The electronic structures and optical properties of boron/phosphorus mono- and co-doped β silicon nitride are studied by the first-principles plane-wave ultrasoft pseudopotential method with the generalized gradient approximation. The results are obtained as follows. The B-doped system has a better stability than the P-doped system, while the P-doped structure has a stronger ionicity. The mono-doping and co-doping can narrow the band gap of β silicon nitride while the co-doping introduces the deep impurity levels and strengthens the localized states. The mono-doping causes the imaginary part of dielectric function, the peaks of absorption spectra and energy loss spectra to red-shift, and their amplitudes to decrease, resulting in a significant difference from the intrinsic state. The co-doping induces the peak of imaginary part of the dielectric function to blue-shift, broadens the energy loss peak, greatly enhances the electronic transition in the high energy region, and controlling the ratio of the numbers of atoms (B and P) in co-doping can achieve a low charged defect concentration, implying its potential application in the field of microelectronics.