在电场下,通过有效质量近似,原子尺度定位 Kohn-Sham 波函数在SiO2/4H-SiC界面上,偏离包络函数。

为了阐明SiO2/4H-SiC界面低通道电导的原因,利用密度泛函理论在施加电场下计算了 SiC导带最小处的波函数。我们发现,4H-SiC(0001)平板的波函数倾向于局限于靠近界面的立方体位点。重要的是,由于导电电子分布在距离界面(<5埃)比有效质量近似值(EMA)所预期的更近处,它们更经常受到界面缺陷的散射。这被认为是(0001)面通道电导率特别低于其他面(如(11-20))的原因。在4H-SiC晶体中,(0001)界面的EMA失效与沿[0001]方向的长结构周期性有关。 To clarify the cause of the low channel conductivity at the SiO2/4H-SiC interface, the wavefunction at the SiC conduction band minimum was calculated using density functional theory under an applied electric field. We found that the wavefunction for a 4H-SiC (0001) slab tends to be localized at the cubic site closest to the interface. Importantly, because the conduction electrons are distributed closer to the interface (< 5 angstroms) than expected from the effective mass approximation (EMA), they are more frequently scattered by interface defects. This is expected to be the reason why the channel conductivity for the (0001) face is particularly low compared with that for other faces, such as (11-20). The breakdown of the EMA for the (0001) interface is related to the long structural periodicity along the [0001] direction in 4H-SiC crystals. 论文链接:http://arxiv.org/pdf/2303.05085v1


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