Awate, Shubham Sukumar
(2023)
Ion Gating of Two-dimensional Materials to Enable New Electronic Device Functionality.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The aggressive scaling of Si-based transistors is becoming increasingly more difficult with conventional materials and cooling limits. This dissertation aims to develop high-speed and low-voltage electronic device functionalities through the use of new materials: two-dimensional (2D) semiconductors and solid electrolytes. Specifically, electric-double-layer-gated transistors (EDLTs) in which ions within an electrolyte control charge transport in the semiconductor by field-effect, are employed to achieve the aims of this dissertation. To provide fundamental insight, finite element modeling is used to describe ion and charge transport in an EDLT. The voltage distribution suggests the possibility of accessing higher charge densities with larger gate voltages while avoiding electrochemistry, which we verified experimentally. The scalability of polymer electrolyte thicknesses down to sub-10 nanometers is modeled and demonstrated experimentally to advance very-large-scale-integration (VLSI) and speed. Pushing beyond the fundamentals, a low-voltage semiconducting-to-metallic phase transition is demonstrated in suspended MoTe_2 through strain, employing a custom-synthesized single ion conductor. The Raman spectroscopic and electrical measurements confirmed the presence of strain-induced metallic phase. This contribution introduces a novel approach for applying strain to the 2D research community, enabling the exploration of fundamental properties and new device mechanisms. The goal of achieving high speed extends to our use of a novel monolayer electrolyte to demonstrate a high-speed, non-volatile switching with program pulse widths down to 50 ns - four orders of magnitude faster than existing flash memory. Two stable ON and OFF states with ON/OFF current ratio larger than 10^3 are measured with 50 ns program pulse. These states can also be maintained for 1000 switching cycles (max. measured) and retained for 28 hours (max. measured) without any external voltage. Lastly, fundamental electrical properties of 2D metal devices are investigated for the first time. In contrast to bulk metals, the charge carrier density in 2D metals is modulated using EDL gating, which can potentially enable applications in optoelectronic devices utilizing 2D metals. Overall, the research reported in this dissertation provides new insights for the field of EDL gating and opens up exciting prospects for the development of low-power, high-speed electronic devices and the exploration of 2D material properties using EDL gating.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
14 September 2023 |
| Date Type: |
Publication |
| Defense Date: |
6 July 2023 |
| Approval Date: |
14 September 2023 |
| Submission Date: |
24 June 2023 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
161 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Electric double layer, 2D materials, ultra-thin electrolyte, solid polymer electrolyte, monolayer electrolyte, High-speed switching, ionomer, single ion conductor, 2D metal |
| Date Deposited: |
14 Sep 2023 13:32 |
| Last Modified: |
14 Sep 2023 13:32 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45040 |
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