利用带间激发的超快瞬态吸收光谱,研究了导电(n型)氮(N)掺杂和半绝缘(SI)钒(V)掺杂6H-SiC晶片的超快载流子复合动力学过程。N杂质和/或固有缺陷的间接复合主导了n型6H-SiC的载流子弛豫,其寿命超过了10 ns。与n型6H-SiC相比,V掺杂对SI-6H-SiC的瞬态吸收具有显著的调制作用,这源于由V深能级的载流子俘获引起的一个额外的载流复合过程。载流子俘获(寿命约为160 ps)比间接复合快2个数量级以上。通过简化能级模型并进行全局分析,研究了6H-SiC的载流子复合机制,准确地获得了6H-SiC的载流子寿命。

The ultrafast transient absorption spectroscopy of interband excitation is utilized to evaluate the ultrafast carrier recombination dynamics in the conductive (n-type) nitrogen (N)-doped and semi-insulating (SI) vanadium (V)-doped 6H-SiC wafers. The carrier relaxation of n-type 6H-SiC with carrier lifetime more than 10 ns is dominated by indirect recombination through N impurities and/or inherent defects. Compared with the n-type 6H-SiC, the V-doped one has a pronounced modulation of transient absorption, resulting from an additional carrier recombination process caused by the carrier trapping of V deep levels. The carrier-trapping with a lifetime of about 160 ps is more than two orders of magnitude faster than the indirect recombination. With a simplified energy level model and the global analysis, the carrier recombination mechanism is investigated and the carrier lifetime of 6H-SiC is determined accurately.