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Enhanced Stability and Performance of Few-Layer Black Phosphorus Transistors by Electron Beam Irradiation

Abstract

Few layer black phosphorus (BP) has recently emerged as a potential graphene analogue due to its high mobility and direct, appreciable, band gap. Fabrication and characterization of field effect transistors (FETs) involves exposure of the channel material to an electron beam (e-beam) in imaging techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and fabrication techniques like electron beam lithography (EBL). Despite this, the effect of e-beam irradiation on BP-FET performance has not been studied experimentally. In this work, we report the first experimental study on the impact of e-beam irradiation on BP-FETs. Electron beam is known to induce defects and structural changes in 2D materials like graphene, MoS2 etc., resulting in deterioration of the device quality. However, for BP-FETs, we observe an improvement in the on-current and carrier mobility along with a decrease in threshold voltage (Vth) on exposure to an e-beam with 15 keV energy for 80 seconds. These changes can be attributed to the capture of electrons by traps near the SiO2-BP interface and reduced BP surface roughness due to e-beam exposure. Hysteresis measurements and physical characterization (i.e. atomic force microscopy (AFM), x-ray photoelectron (XPS) and Raman spectroscopies) validate these mechanisms. Reduced hysteresis indicates occupation of the traps, AFM surface scans indicate reduced surface roughness and XPS data shows reduced phosphorus oxide (POx) peak immediately after exposure. Raman measurements indicate a probable structural change due to the interaction between e-beam and BP which could result in better stability.

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Publication details

The article was received on 27 Feb 2018, accepted on 09 May 2018 and first published on 17 May 2018


Article type: Paper
DOI: 10.1039/C8NR01678J
Citation: Nanoscale, 2018, Accepted Manuscript
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    Enhanced Stability and Performance of Few-Layer Black Phosphorus Transistors by Electron Beam Irradiation

    N. Goyal, N. Kaushik, H. Jawa and S. Lodha, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C8NR01678J

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