Project

Current Status

Atomically Resolved Scanning Probe Microscopy on Electronic Characterization of Advanced Semiconductors

Team Members

PI

Prof. Ya-Ping Chiu, Distinguished Professor

Dept. Physics, National Taiwan University

Prof. Yi-Chun Chen, Distinguished Professor

Dept. Physics, National Cheng Kung University

Prof. Chun-Wei Chen, Distinguished Professor

Dept. Materials Science and Engineering, National Taiwan University

Introduction

When the size of the advanced semiconductors approaches to the atomic level, the performance of the devices is dominated by point defects and the electronic structure at heterointerfaces. To characterize and further control the electrical properties, such as the band alignment at interfaces, the work function, and the carrier concentration of the low-dimensional semiconductors becomes a key issue in advanced semiconductors.

Considering the critical carrier concentration in nanoscale and defect-induced trap densities governing the applications of devices, the proposal convenes the research teams long term specializing in developing unique scanning probe microscopic techniques and cutting-edge semiconductor materials for scanning probe characterizations to directly establish the correlation between the atomic configurations and the electronic structures of defects and detect the carrier distribution in semiconductors to achieve “Atomic-level cutting-edge scanning probe characterization platform”.

Scanning probe characterization techniques, including STM, cross-sectional STM, and AFM probing techniques.

Phase I - Achievements

Research collaborated results of the team: The work develop a two-step doping method for the contact doping of a monolayer MoS₂ Au-contact device, and confirmed the doping results through STM images. We achieve a record-high sheet conductance (0.16 mS*sq^-1, without gating) and high mobility and carrier concentration (4.1*10¹³cm^-2) of monolayer MoS₂, and the contact resistance with gold was reduced to . Research result has been published in the internationally renowned academic journal “ACS Nano”: “Hysteresis-Free Contact Doping for High-Performance Two-Dimensional Electronics”, ACS Nano 2023 17 (3), 2653-2660.

(a) STM image of pristine MoS₂ on the SiO₂ substrate. Small white spots are the sulfur vacancy sites.

(b) STM image of the two-step-doped MoS₂. The white double-cross shapes are the regions with dopants on top of the MoS₂.

Ref.: ACS Nano 17 (3), 2653-2660 (2013).

This work demonstrates a combination of light-modulated scanning tunneling microscopy and the quasiparticle interference (QPI) technique to offer a directly accessible approach to reveal and quantify the unexplored momentum-forbidden electronic quantum states in transition metal dichalcogenide (TMD), and provide the opportunity to explore the electronic behavior of the valley degree of freedom for future potential optoelectronic technological applications. Research result has been published in the internationally renowned academic journal “ACS Nano”: “Directly Visualizing Photoinduced Renormalized Momentum-Forbidden Electronic Quantum States in an Atomically Thin Semiconductor” ACS Nano 2022 16 (6), 9660–9666.

(a) The STS map corresponds to thescanning region on the topographic picture and reveals the QPI patterns in real space.
(b) The schematic diagram of the energy renormalization effect on the Q valley from the photoexcited carriers’ occupation.
Ref.: ACS Nano 16 (6), 9660–9666 (2022).

Current Status

Atomically Resolved Scanning Probe Microscopy on Electronic Characterization of Advanced Semiconductors

PI

Prof. Ya-Ping Chiu, Distinguished Professor

Co-PI

Prof. Yi-Chun Chen, Distinguished Professor

Prof. Chun-Wei Chen, Distinguished Professor

A世代前瞻半導體技術專案計畫｜ANGSTROM SEMICONDUCTOR INITIATIVE

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