N-Al共掺杂4H-SiC的第一性原理计算

First Principle Calculation of N-Al Co-doped 4H-SiC

采用基于密度泛函理论的第一性原理平面波超软赝势方法,计算本征、N单掺杂、Al单掺杂及N-Al共掺杂4H-SiC的电子结构和光学性质。结果表明:N-Al共掺杂导致4H-SiC晶格膨胀,4H-SiC的禁带宽度减小,同时在4H-SiC禁带中引入了杂质能级;N、Al的单掺杂增加了4H-SiC对红外波段和可见光波段的响应,N-Al共掺杂不存在该现象;N-Al共掺杂4H-SiC较本征4H-SiC在紫外波段出现一个更大的透射窗口,吸收系数略小于本征4H-SiC的。

Electronic structures and optical property of pure 4H-SiC,N doped,Al doped and N-Al co-doped 4H-SiC were calculated using the plan wave ultra-soft pseudopotential method based on the density functional theory. The results indicate that the lattice is expanded and the forbidden band width is decreased due to the doping. The doping introduces impurity energy into the forbidden band. Doping of N or Al extends the visible and infrared absorption of 4H-SiC. The N-Al co-doped 4H-SiC does not show this phenomenon and has a winder transmission window and a lower absorption coefficient in ultraviolet band than the pure 4H-SiC.