Graduation Semester and Year

2020

Language

English

Document Type

Thesis

Degree Name

Master of Science in Materials Science and Engineering

Department

Materials Science and Engineering

First Advisor

Jin Seong Koh

Second Advisor

Yaowu Hao

Third Advisor

Kyungsuk Yum

Abstract

The thermodynamic limit of the subthreshold slope to 60mV/decade at 300K forces MOSFET devices to use high supply voltages (> 0.5V) and therefore dissipate a lot of energy. This physical limitation of transistors is a direct consequence of thermal excitation of electrons. This study investigates a new transistor architecture capable of suppressing thermally excited electrons using a quantum well as an energy filter. The energy filter consists of a 2nm SiO2 tunneling barrier and a 2nm Quantum Well (QW) layer of Cr2O3 sandwiched between Ni electrodes and a channel of Si. Transistors having this QW energy filter have been fabricated using CMOS-compatible processes and materials. Their IV characteristics have been compared with control samples without tunneling barriers and QW layers to investigate suppression of thermally excited electrons. The three device configurations fabricated and studied include: sample with no tunneling barrier and no QW layer, sample with tunneling barrier only and sample with both tunneling barrier and QW layer. Gate modulation was observed in all three device configurations, demonstrating successful fabrication of transistors. These gate modulations, however, were observed only at large drain voltage (> 2V), indicating an efficient gate coupling was not established, which would obscure the energy filtering effect that might have been present. A future study may focus on establishing an efficient gate coupling.

Keywords

Cold-electron transistor, Energy filtering, Thermally excited electrons, Gate coupling, Fermi-Dirac excitation

Disciplines

Engineering | Materials Science and Engineering

Comments

Degree granted by The University of Texas at Arlington

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