Doping of traditional semiconductors has enabled technological applications in modern electronics by tailoring their chemical, optical and electronic properties. However, substitutional doping in two-dimensional semiconductors is at a comparatively early stage, and the resultant effects are less explored. In this work, we report unusual effects of degenerate doping with Nb on structural, electronic and optical characteristics of MoS₂ crystals. The doping readily induces a structural transformation from naturally occurring 2H stacking to 3R stacking. Electronically, a strong interaction of the Nb impurity states with the host valence bands drastically and nonlinearly modifies the electronic band structure with the valence band maximum of multilayer MoS₂ at the Γ point pushed upward by hybridization with the Nb states. When thinned down to monolayers, in stark contrast, such significant nonlinear effect vanishes, instead resulting in strong and broadband photoluminescence via the formation of exciton complexes tightly bound to neutral acceptors.

中文翻译：

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通过替代掺杂重新配置MoS2的晶体和电子结构。

掺杂传统半导体可以通过调整其化学，光学和电子特性，使其在现代电子技术中得到应用。然而，二维半导体中的替代掺杂还处于相对较早的阶段，因此对这种效应的研究较少。在这项工作中，我们报告了简并的Nb掺杂对MoS ₂晶体的结构，电子和光学特性的异常影响。掺杂容易引起从自然发生的2H堆叠到3R堆叠的结构转变。在电子上，Nb杂质态与主价带的强烈相互作用极大地和非线性地改变了多层MoS ₂的价带最大值的电子能带结构通过与Nb杂化将γ点向上推。与之形成鲜明对比的是，当减薄为单层时，这种显着的非线性效应便消失了，而是通过形成与中性受体紧密结合的激子复合物而产生了强而宽带的光致发光。