论文标题
二维晶体中P-I-N连接的激子定位
Exciton localization on p-i-n junctions in two-dimensional crystals
论文作者
论文摘要
我们考虑使用在二维晶体中定义的模型P-I-N结的中性激子：Mose $ _2 $和磷烯，采用有效的质量汉密尔顿的变分方法。连接处的非均匀电场阻止了质量中心的分离。变分解决方案在真实空间中提供了激子密度，并解释了由于激子定位而导致的动能。 对于跨交界处的潜在步骤的低值，激子占据的区域比连接点的名义范围大得多，并且能量对步骤的值根本不敏感。激子在接口区域内的定位伴随着当地电场引起的偶极矩的出现。仅当步骤足够大时，偶极矩才成为电势步骤的线性函数。因此，对步骤值的能量依赖性是非促谁的。我们证明，激子的位置不完全位于连接处的中心，而是在侧面，这在较重的载体上更有利：电子或孔。
We consider a neutral exciton localized on a model p-i-n junction defined in a two-dimensional crystal: MoSe$_2$ and phosphorene, using a variational approach to the effective mass Hamiltonian. The non-homogeneous electric field at the junction prevents the separation of the center of mass. The variational solution provides the exciton density in the real space and accounts for the kinetic energy due to the exciton localization. For low values of the potential step across the junction, the exciton occupies an area which is much larger than the nominal range of the junction and the energy remains essentially insensitive to the value of the step. Localization of the exciton within the junction area is accompanied by the appearance of the dipole moment induced by the local electric field. The dipole moment becomes a linear function of the potential step only when the step is sufficiently large. In consequence, the energy dependence on the step value is non-parabolic. We demonstrate that the exciton gets localized not exactly at the center of the junction but on the side which is more energetically favourable for the heavier carrier: electron or hole.
