EAGER: Black Phosphorus For Tunable Wide Bandwidth Sensor Arrays

University Of North Texas, Denton TX

Investigators

Abstract

Abstract: Black Phosphorus for Tunable Wide-bandwidth Sensor Arrays Nanocarbons 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.