EAGER: Black Phosphorus For Tunable Wide Bandwidth Sensor Arrays

摘要：在过去的几十年里，碳纳米材料引起了研究人员的关注，如七叶树球、碳纳米管、碳纳米纤维和石墨烯。这种丰富多样的纳米碳选择是可能的，因为纳米碳的晶体结构多种多样，其中一种形式是二维（2D）石墨烯，一种分层材料。二维石墨烯使研究人员能够探索其他二维层状材料，如过渡金属二硫族化合物、各种氧化物、氮化物和粘土。除了碳之外，最近又增加了一种材料，即磷，它在固体状态下的结构也有很大的多样性，从正交黑磷、立方白磷、单斜紫色磷、纤维红磷和无定形红磷。近年来，磷的层状形态引起了人们的广泛关注，特别是黑磷具有独特的褶皱蜂窝晶格。然而，与石墨不同，黑磷是一种直接带半导体，使其成为光电子学和传感应用的有吸引力的材料。本文提出的工作重点是了解黑磷的有趣的电子和光电子特性，并利用这种材料开发新的光电传感器件。与大多数具有更高间接带隙的过渡金属二硫族化合物不同，黑磷具有0.3 eV的窄直接带隙，这表明黑磷具有面向近红外和中红外区域的传感和探测器应用前景。此外，可以通过控制层厚来设计黑磷的带隙；带隙随层数的减少而增大，单层磷烯的带隙可达2 eV。因此，设计具有不同层数的黑磷器件阵列中的层数应该能够在宽光谱范围内进行光探测。我们将利用黑磷的奇异特性，并将这种新材料与二硫化钼（MoS2）结合起来，展示在从可见光到红外（IR）的宽光谱范围内运行的高性能可调谐传感器阵列。该提案的新颖之处是利用黑磷的可调带隙特性，其载流子的高迁移率来实现快速响应时间探测器，同时，二维（2D）范德华异质结构之间的原子尖锐界面应该通过减少困扰掺杂梯度结性能的暗电流来产生超灵敏的探测器。

Abstract: Black Phosphorus for Tunable Wide-bandwidth Sensor ArraysNanocarbons have captured the attention of researchers over the past several decades with materials such as buckeyballs, carbon nanotubes, carbon nanofibers and graphene. This rich variety of nanocarbon choices is possible due to the diverse crystalline structures of nancarbons, one form of which is two-dimensional (2D) graphene, a layered material. Two-dimensional graphene has enabled researchers to explore other 2D layered materials, such as the transition metal dichalcogenides, a wide variety of oxides and nitrides and clays. A recent addition to the suite of materials beyond carbon is phosphorus which also shows great diversity in its structures in the solid state, ranging from orthorhombic black phosphorus, cubic white phosphorus, monoclinic violet phosphorus, fibrous red phosphorus and amorphous red phosphorus. Recently, a great deal of attention has been paid to the layered form of phosphorus, specifically black phosphorus which has a unique puckered honeycomb lattice. However, unlike graphite, black phosphorus is a direct band semiconductor in the bulk making it an attractive material for optoelectronics and sensing applications. The focus of the work proposed here is to understand the intriguing electronic and optoelectronic properties of black phosphorous and to develop novel optoelectronic sensing devices from this material. Black phosphorus has a narrow direct band gap of 0.3 eV in the bulk, unlike most of the transition metal dichalcogenides which have much higher, indirect band gaps, suggesting that black phosphorus has prospects for sensing and detector applications targeted for the near IR and mid-IR regimes. Moreover, the band gap of black phosphorus can be engineered through control of layer thickness; the band gap increases with decreasing layer number, reaching 2 eV for single layer phosphorene. Therefore, engineering the layer number in arrays of black phosphorus devices with varying layer number should enable photo-detection over a broad spectral range. We will utilize the exotic properties of black phosphorus and integrate this novel material with molybdenum disulphide (MoS2) to demonstrate high performance tunable sensor arrays operational over a wide spectral regime from the visible to the infrared (IR). The novel features of this proposal are to capitalize on the tunable band gap properties of black phosphorus, the high mobility of its carriers to enable fast response time detectors, and at the same time, the atomically sharp interfaces between two-dimensional (2D) van der Waals heterostructures should yield ultra-sensitive detectors by reducing dark currents that plague the performance of doped-graded junctions.