December 1 - 6, 2024
Boston, Massachusetts
Symposium Supporters
2024 MRS Fall Meeting & Exhibit
EL03.20.05

Minimizing Defects in Wafer-Scale WSe2 Monolayers

When and Where

Dec 6, 2024
4:30pm - 4:45pm
Hynes, Level 3, Room 302

Presenter(s)

Co-Author(s)

Yi Wan1,Lin-Yun Huang1,Haoming Liu1,Li Lain-Jong1

The University of Hong Kong1

Abstract

Yi Wan1,Lin-Yun Huang1,Haoming Liu1,Li Lain-Jong1

The University of Hong Kong1
Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted great attention as they prospect of continuing Moore's law. Recent advancements in wafer-scale single crystal 2D TMD growth and device technologies have demonstrated their scalable potential and excellent electronic performance, approaching the projection made by the International Roadmap for Devices and Systems (IRDS). However, while notable progress has been achieved with n-type characteristics in MoS2, the performance of p-type WSe2 remains suboptimal, primarily due to the lack of efficient bottom-up synthesis methods for high-quality WSe2 monolayers.
To address this gap, we have developed a hydroxide vapor phase deposition (OHVPD) approach for synthesizing high-quality p-type monolayer WSe2. By introducing moisture into the epitaxial process, tungsten hydroxide acts as an immediate that provides a lower sulfurization energy pathway, facilitating the growth of WSe2 with significantly reduced point defect density. Combining this with C-plane sapphire substrates having single exposed surfaces, we have achieved 2-inch single-crystal WSe2 with low defect density.
Moreover, our systematic study of the effect of the H2 to H2O ratio on the quality of WSe2 provides insight into the fundamental mechanisms at play. Scanning tunneling microscopy (STM) characterization reveals that OHVPD-WSe2 exhibits a total defect density of 7.8×1011 cm-2, an order of magnitude lower than that of conventionally grown CVD-WSe2. Optical characterizations, including cryogenic photoluminescence (PL), show negligible defect emission, confirming its intrinsic properties. Field-effect transistor (FET) devices based on our OHVPD-WSe2 display typical p-type characteristics, with a peak mobility of 110 cm2V-1s-1 and an average mobility of 87 cm2V-1s-1.

Keywords

2D materials | chemical vapor deposition (CVD) (deposition) | defects

Symposium Organizers

Deji Akinwande, The University of Texas at Austin
Cinzia Casiraghi, University of Manchester
Carlo Grazianetti, CNR-IMM
Li Tao, Southeast University

Session Chairs

Roshni Babu
Carlo Grazianetti

In this Session