Modification of Electronic and Vibrational Properties of Doped Black-P Films
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Modification of Electronic and Vibrational Properties of Doped Black-P Films Sayan Sarkar1, Prashant K Sarswat 1, and Michael L. Free1 1
Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT84112, USA
ABSTRACT Black phosphorus (black-P) research has been the most absent for 100 years since its date of first synthesis in 1914 among all the polymorphs of phosphorus. However, recently it has been re-examined due to its specific puckered single layer geometry. Few or single atomic layer forms of black-P can be isolated using techniques such as micromechanical or liquid exfoliation. However, the exfoliation techniques limit the use of black-P, hence a method of black-P layer deposition onto a substrate is needed. Few or atomic layer deposition of black-P leads to substratematerial interactions and a possible appearance of a band gap opening at the K point. Hence, a series of experiments were conducted in order to grow black-P on different substrates. With the incorporation of doping elements, there was substantial modification in the vibrational and electrical properties. It was observed that sulfur and boron doped films exhibit improved electrical and electronic properties as compared to pristine black-P. Density functional theory predicts significant changes in the band structure and density of states as a consequence of doping. The effects of doping was also reflected in Raman A1g mode. The shift in peak position was also found to be consistent with molar mass of dopants. INTRODUCTION Among the constituents of the two-dimensional systems beyond graphene, phosphorenethe single- or few-layer form of black phosphorus is an emerging material due to its potential utility in electronics, optoelectronics, photonics, catalysis and other applications. From the point of view of industrial usage, phosphorus was always functional, having being used in matchsticks, fireworks, and fertilizers [1], but its application was limited due to its structural instability and strong toxicity [1]. But after a prolonged period of dormancy of about a century, phosphorene has recently been re-explored as a two-dimensional layered material with great interest in the field of condensed matter physics and material science. Highly tunable direct band gap [2], substantial carrier mobility [2] and a high on/off ratio [2-3] attributes make it a prospective candidate for digital transistor applications and Nano-photonics. Moreover, quantum mechanical calculations envisaged striking thermoelectric figures of merit [4-5], optical anisotropy, Peierls-distortion [6] and layer-restricted band gap due to quantum confinement. It is also the most stable allotrope of phosphorus including white, red and violet phosphorus [7-11]. Due to a stacked layered structure and meager van der Waals (vdWs) interlayer interactions, exfoliation of its layers is facile. In comparison to the other 2D materials, phosphorene exhibits a great amount of anisotropy. It exhibits a corrugated structure along the armchair direction (Fig. 1a), but along the zi
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