Investigation of the subustituional behavior and the electrical activation of implanted P and N impurities in SiC

1.注入氮杂质在6 H-SiC中的激活过程在氮浓度低于2×10 ~ 4<20>/cm ~ 3的范围内，1200℃退火可实现电激活。1200℃退火也促进了N杂质对SiC中Si亚晶格位的替代。但是，在N浓度大于2×10^<20>/cm ^3的范围内，由N杂质激活的自由电子数随N浓度的增加而减少。在这种情况下，过量注入的N杂质优先占据SiC的间隙位置而不是替代位置. 6 H-SiC中注入P杂质的激活过程6 H-SiC中注入P杂质的激活过程取决于注入层是否被注入工艺非晶化。在非晶化注入的情况下，注入的P杂质可以占据Si亚晶格位置，而非晶化的注入层甚至在1000℃下通过退火再结晶，这立即导致注入的P杂质的电激活。但是，在较高的温度下退火诱导的外扩散和重新分布的P注入SiC中的杂质。另一方面，在使用“热”注入技术而不使注入层非晶化的情况下，通过提高退火温度来增加Si亚晶格位置上的P杂质浓度，这导致SiC中的自由电子浓度增加。然而，所获得的自由电子浓度的“热”注入的SiC是低于非晶化注入层的情况下。结果表明，部分注入的P杂质占据了SiC的间隙位。

1. Activation Process of the implated N impurities in 6H-SiCIn the N concentration range below 2×10^<20>/cm^3, the electrical activation is achieved by annealing at 1200℃. The substitution of the N impurities on Si sublattice sites in SiC is also promoted during the annealing at 1200℃. However, in the N concentration range above 2×10^<20>/cm^3, the number of free electrons activated from N impurities is decreased with the increase of the N concentration. In this regime, it is suggested that the excess implanted N impurities preferably occupy the interstitial sites in SiC rather than the substitutional sites.2. Activation process of the implanted P impurities in 6H-SiCThe activation process of the implanted P impurities in 6H-SiC depends on whether the implanted layer is amorphized by implantation process. In the case of the implantation with the amorphization, the implanted P impurities can occupy the Si sublatties sites while the amorphized implant layer is re-crystallized by annealing even at 1000℃, which leads immediately the electrical activation of the implanted P impurities. However, in the annealing at higher temperature induces the out-diffusion and the redistribution of the implanted P impurities in SiC. On the other hand, in the case of the implantation without the amorphization of the implanted layer using "Hot" implantation technique, the concentration of the P impurities on the Si sublattice sites is increase by increasing the annealing temperature, which results in the increase of the free electron concentration in SiC. However, the obtained free electron concentration of the "Hot" implanted SiC is lower than the case of the amorphized implant layer. It is suggested that a part of the implanted P impurities occupy the interstitial sites in SiC.