Off-campus WSU users: To download campus access dissertations, please use the following link to log into our proxy server with your WSU access ID and password, then click the "Off-campus Download" button below.

Non-WSU users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Access Type

WSU Access

Date of Award

January 2016

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Physics and Astronomy

First Advisor

Zhixian Zhou

Abstract

ABSTRACT

TWO-DIMENSIONAL LOW-RESISTANCE CONTACTS FOR HIGH PERFORMANCE WSe2 and MoS2, TRANSISTORS

by

Hsun-jen Chuang

May 2016

Advisor: Dr. Zhixian Zhou

Major: Physics

Degree: Doctor of Philosophy

Two-dimensional layered materials beyond graphene such as transition metal dichalcogenides (TMDs) have attracted a lot of interests due to their superior property in many aspects. In this work, I am focusing on two TMD materials: WSe2 and MoS2. The main objective this work is to develop novel approaches to fabricating low-resistance ohmic contacts to TMDs for low power, high performance electronic applications. First, we used graphene as electrical contacts for WSe2 field-effect transistor with superior performance, including a high ON/OFF ratio of >107 at 170 K, large electron mobility of ~330 cm2V-1s-1 and he hole mobility of ~270 cm2V-1s-1 at 77 K, and low contact resistance of ~ 2kΩ µm. Second, we developed a novel 2D to 2D contacts strategy2 for a variety of TMDs by van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. The high intrinsic behavior of the device is revealed, where it exhibits low contact resistances of ~0.3 kΩ µm, on/off ratios up to > 109 as well as two-terminal field-effect hole mobility μFE ≈ 2×102 cm2 V-1 s-1 at 300K, which increases to > 6×103 cm2 V-1 s-1 down to 10K. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and other 2D materials as the channel materials in post-silicon electronic.

Off-campus Download

Share

COinS