Fan Shuangqing, Tang Xiaodong, Zhang Daihua, Hu Xiaodong, Liu Jing, Yang Lijun, Su Jie
School of Electronic and Information Engineering, Qingdao University, Qingdao 266071, China.
Nanoscale. 2019 Aug 15;11(32):15359-15366. doi: 10.1039/c9nr05343c.
The controllable and wide-range modulation of the carrier type and mobility in atomically thin two-dimensional (2D) materials is one of the most critical issues to be addressed before 2D materials can be practically used for future electronic and optoelectronic devices. In this work, we propose using a novel surface charge transfer mechanism to accomplish the controllable and wide-range modulation of the carrier type and mobility in 2D materials. Our methodology uses a solution of triphenylboron (TPB) to physically coat 2D materials; the TPB molecule contains positive and negative charge centers that are spatially separable when induced by an electrical field. Consequently, the TPB can transfer either positive or negative charges to 2D materials depending on the direction of the applied electrical field and thus enhance the ambipolar behavior of the 2D-material FET. This method is so versatile that seven types of 2D materials including graphene, black phosphorus and five transition metal dichalcogenides (TMDCs) can be modulated to strong ambipolar behavior with significantly increased conduction. In addition, selectively suppressing or enhancing the negative charge center enables solely p-type and n-type doping. We also accomplish the precise tuning of carrier mobility in TMDCs from ambipolar to p-type by coating a mixture of TPB/BCF in certain concentration ratios.
在二维材料能够实际应用于未来的电子和光电器件之前，实现原子级薄的二维（2D）材料中载流子类型和迁移率的可控且宽范围调制是最关键的问题之一。在这项工作中，我们提出使用一种新型的表面电荷转移机制来实现二维材料中载流子类型和迁移率的可控且宽范围调制。我们的方法是使用三苯基硼（TPB）溶液对二维材料进行物理包覆；TPB分子包含正电荷中心和负电荷中心，在电场诱导下，它们在空间上是可分离的。因此，根据施加电场的方向，TPB可以将正电荷或负电荷转移到二维材料上，从而增强二维材料场效应晶体管的双极性行为。这种方法非常通用，包括石墨烯、黑磷和五种过渡金属二硫属化物（TMDCs）在内的七种二维材料都可以被调制为具有显著增强导电性的强双极性行为。此外，选择性地抑制或增强负电荷中心能够实现单一的p型和n型掺杂。我们还通过以特定浓度比例包覆TPB/BCF的混合物，实现了TMDCs中载流子迁移率从双极性到p型的精确调控。
