Exploration of surface states in a monolayer MoS2 transistor by pulsed gating

Zhongyuan Lu

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2016-188
December 1, 2016

http://www2.eecs.berkeley.edu/Pubs/TechRpts/2016/EECS-2016-188.pdf

Two-dimensional (2D) materials have interested researchers all over the world for years due to their unique properties. Their ultra-thin thicknesses, lack of dangling bonds, and excellent thermal stabilities make them promising material candidates for use in next generation nanoelectronic devices. Graphene was the first 2D material discovered and has extremely high carrier mobility (>10^5 cm^2/V-sec). However, it lacks a finite band gap, restricting its potential use in field-effect transistors (FETs) to only the channel. Alternatively, MoS2 is a compound 2D material with a finite band gap and low dielectric constant. As a result, it has recently been generating great interest in both academia and industry for its potential use in switchable devices.

In this work, we have explored the interface states that form between the channel of a monolayer MoS2 transistor and a high-k gate dielectric. These interface states result in a large hysteresis in the transfer characteristic (i.e. drain current versus gate voltage) of the transistor. By applying carefully designed pulses to the gate of the transistor, we show that it is possible to both understand the nature of the interface states and minimize the hysteresis. This allows for reliable extraction of material parameters such as mobility from the transfer characteristics.

Advisor: Sayeef Salahuddin


BibTeX citation:

@mastersthesis{Lu:EECS-2016-188,
    Author = {Lu, Zhongyuan},
    Editor = {Salahuddin, Sayeef and Bokor, Jeffrey},
    Title = {Exploration of surface states in a monolayer MoS2 transistor by pulsed gating},
    School = {EECS Department, University of California, Berkeley},
    Year = {2016},
    Month = {Dec},
    URL = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2016/EECS-2016-188.html},
    Number = {UCB/EECS-2016-188},
    Abstract = {Two-dimensional (2D) materials have interested researchers all over the world for years
due to their unique properties. Their ultra-thin thicknesses, lack of dangling bonds, and
excellent thermal stabilities make them promising material candidates for use in next
generation nanoelectronic devices. Graphene was the first 2D material discovered and has
extremely high carrier mobility (>10^5 cm^2/V-sec). However, it lacks a finite band gap,
restricting its potential use in field-effect transistors (FETs) to only the channel.
Alternatively, MoS2 is a compound 2D material with a finite band gap and low dielectric
constant. As a result, it has recently been generating great interest in both academia and
industry for its potential use in switchable devices.

In this work, we have explored the interface states that form between the channel of a
monolayer MoS2 transistor and a high-k gate dielectric. These interface states result in a
large hysteresis in the transfer characteristic (i.e. drain current versus gate voltage) of the
transistor. By applying carefully designed pulses to the gate of the transistor, we show
that it is possible to both understand the nature of the interface states and minimize the
hysteresis. This allows for reliable extraction of material parameters such as mobility
from the transfer characteristics.}
}

EndNote citation:

%0 Thesis
%A Lu, Zhongyuan
%E Salahuddin, Sayeef
%E Bokor, Jeffrey
%T Exploration of surface states in a monolayer MoS2 transistor by pulsed gating
%I EECS Department, University of California, Berkeley
%D 2016
%8 December 1
%@ UCB/EECS-2016-188
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/2016/EECS-2016-188.html
%F Lu:EECS-2016-188