本文利用阴极荧光(CL)和选择性刻蚀的方法对4H-SiC同质外延材料中基面位错的发光特性进行了研究.结果表明螺型基面位错(BTSD)和混合型基面位错(BMD)分别具有绿光和蓝绿光特性,其发光峰分别在530 nm附近和480 nm附近.从测试结果中还发现BMD的发光位较BTSD有所蓝移,分析认为BTSD位错芯附近原子沿伯格斯矢量方向只受到拉应力,致使禁带宽度变窄,而BMD同时具有螺型位错的分量和刃型位错的分量,正是刃型位错中部分原子受到压应力的作用,导致禁带宽度增宽,从而使得BMD的发光波长比BTSD短.%Luminescence properties of basal plane dislocations in 4H-SiC are studied by means of cathodoluminescenee (CL)and defect selective etching. It is found that basal plane screw dislocations (BTSD ) and basal plane mixed dislocations (BMD) have green and blue-green luminescence properties, respectively. The spectrum peaks near 530 nm and 480 nm correspond to BTSD and BMD, respectively. It is found from measurement that the luminescence peak from BMD is blue-shifted. The atoms of BTSD near the dislocation core are affected by tensile stress along the Burger's vector direction,leading to its band gap narrowed. In addition, the Burger's vector of BMD has both screw and edge components. It is the edge component that is responsible for the band gap broadening. In other words, the wavelength from BMD is shorter than that from BTSD.
展开▼
