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基于文献报道的4H-SiC材料的各向异性物理特性,首次提出4H-SiC基超结器件的各向异性物理模型,并对不同晶向的碰撞电离分别进行考虑。基于该模型,我们对(0001)和(1120)两种晶向晶圆的4H-SiC超结器件的电学特性进行了研究。与(1120)晶圆相比,(0001)晶圆的碰撞电离系数较小,可以实现更高的击穿电压VB。由于碰撞电离各向异性,与传统4H-Si C基器件相比,超结器件的二维电场分布可以将(1120)晶圆器件的击穿电压VB从(0001)晶圆器件的60%提高到72%。
Based on the reported anisotropic physical properties of 4H-SiC materials, the anisotropic physical model of 4H-SiC-based superjunction devices is first proposed and the impact ionization in different crystal orientations is considered respectively. Based on this model, we investigated the electrical properties of 4H-SiC superjunction devices with (0001) and (1120) wafers. The impact ionization coefficient of the (0001) wafer is smaller than that of the (1120) wafer, resulting in a higher breakdown voltage VB. Due to the impact ionization anisotropy, the two-dimensional electric field distribution of the superjunction device increases the breakdown voltage VB of the (1120) wafer device from 60% of the (0001) wafer device as compared to the conventional 4H-Si C based device To 72%.