Browsing by Subject "MOSFETs"

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    Engineering Novel Transistors Based On Black Phosphorus
    (2019-02) Robbins, Matthew
    Black phosphorus (BP), a layered 2D semiconductor that can be isolated to one monolayer thicknesses re-emerged in 2014 because of its promise for use in applications such as high performance MOSFETs, optoelectronic devices, novel devices like tunneling-field-effect-transistors (TFETs), and flexible electronics. The promise of BP comes from its unique material properties such as a high mobility, crystal anisotropy, a tunable direct band gap, an anisotropic effective mass, and the ability to scale to sub-1 nm thicknesses while retaining good electronic properties. These properties make BP particularly interesting as a possible post-silicon channel material in advanced logic transistors which could enable the continuation of transistor scaling beyond the foreseeable future. However, most experimental demonstrations of BP transistors have displayed poor OFF-state performance caused by gate-induced-drain-leakage (GIDL) which limits the device's overall usefulness. In this dissertation, novel BP transistors that utilize the unique properties of BP to improve OFF-state performance are demonstrated. These novel devices include a heterostructure BP MOSFET which utilizes the thickness-tunable band gap of BP to supress GIDL current, an electrostatically doped BP MOSFET which takes advantage the thin body of BP with a novel device structure used to effectively dope the source and drain regions of the BP, to again suppress GIDL current, and BP TFETs which utilize the anisotropic effective mass in order to open a path for realizing transistors with a subthreshold slope (SS) of less than 60 mV/dec in BP.
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    High-k Gate dielectric materials for CMOS.
    (2010-08) McCarthy, Ivana
    Abstract summary not available
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    Two-Dimensional Black Phosphorus for High Performance Field Effect Transistors
    (2017-06) Haratipour, Nazila
    Two-dimensional (2D) materials are a potential platform for scaled logic devices, sensor applications, flexible electronics and other innovative device concepts. Black phosphorus (BP) has recently emerged as a new promising layered semiconductor due to its unique material properties. BP has high electron and hole mobility, tunable band-gap ranging from 0.3 eV (bulk) to 1-2 eV (monolayer) and highly asymmetric effective mass. BP metal-oxide-semiconductor field-effect transistors (MOSFETs) have the potential to outperform other 2D semiconductors mainly due to the lighter effective mass of BP, which leads to higher mobility, and narrower band gap, which can reduce contact resistance due to the Schottky barrier height lowering. In this dissertation, BP n- and p-type MOSFETs with record performance are demonstrated. A comprehensive experimental and theoretical evaluation of the design and operating parameters that limit the off-state performance and subthreshold slope in BP MOSFETs is performed. Next, for the first time, the effect of asymmetric crystal orientation on BP MOSFET performance is quantified and the anisotropic mobility in a realistic MOSFET geometry is analyzed. Finally, contact engineering is utilized to achieve record-low contact resistance in BP p-MOSFETs.