Few-Layer MoS2 p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation

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• 作者：Ankur Nipane ; Debjani Karmakar ; Naveen Kaushik ; Shruti Karande ; Saurabh Lodha
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：February 23, 2016
• 年：2016
• 卷：10
• 期：2
• 页码：2128-2137
• 全文大小：717K
• ISSN：1936-086X

文摘

P-type doping of MoS₂ has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS₂. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS₂. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS₂ field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10⁴ are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS₂ layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS₂. Pre-existing sulfur vacancies are shown to enhance the doping level significantly.