Research - Surface Electron Dynamics

Home
Research Highlights

RESEARCH
Measurement Standardization
Surface Dynamics
Organic Semiconductors
Nanomaterial Surfaces
2D Materials

PUBLICATIONS
Journal Articles
Thesis Work
Presentations

PEOPLE
Group Members
How to get here
Open Positions
Collaborations

PHOTO GALLERY
Members
Lab

 

Dr. JeongWon Kim

Staff Scientist

Professor (UST)

Division of Industrial Metrology

Korea Research Institute of Standards & Science
267 Gajeong-Ro

Daejeon 34113

Republic of Korea

Phone
Fax:

+82-(0)42-868-5761

+82-(0)42-868-5032

Emerging of ultrafast pulsed lasers enabled the study of carrier dynamics of solid system. Using pump-probe technique, we measure two photon photoemission spectra on various surfaces. Those are very important to understand carrier generation, separation and recombination procedures upon excitation. Moreover, other properties of photoelectrons such as momentum, polarization dependence, decoherence are deduced.

 

 Ultrafast Carrier Dynamics of molecules on GaAs Surface

Two Photon Photoemission (2PPE) combined with femtosecond laser gives information of fast carrier dynamics on surfaces. At organic/inorganic hetero interfaces, energy level alignment plays an important role in the charge carrier transfer. While C60 opens a new channel for electron transfer from GaAs, CuPc causes hole transfer from GaAs and delayed triplet state formation in CuPc.

 Abstract Image

Pseudo 2D Plot of 2PPE spectra of clean GaAs(001)

Abstract Image 

Delayed triplet formation at CuPc/GaAs interface

 

 Electron Energy Distribution from Local Areas

For the first time with femtosecond time-resolved pump-probe method and TOF-PEEM, we demonstrated time-, energy-, and spatial-resolved experiments in the Ag coated silicon nanostructure. In two different region of this system the ultrafast electron relaxation dynamics was investigated. As the report of Schönhense group, we also observed the hot spots in nanostructure were created by 2PP process and were characterized by a slightly lower work function than homogeneous regions. Time-resolved photoelectron spectra show lower energy shifts in both regions but the spectra of the bright region show more dramatic energy shifts. Space charge effect was considered as one of spectral broadening mechanisms.

2PPE UV-PEEM image of a nanostructure

2PPE spectra of the bright and the dark regions

 

 

대전시 유성구 가정로 267 한국표준과학연구원 산업응용측정본부 나노구조측정센터

첨단인증동 (313) B-16, Tel. 042-868-5977

대전시 유성구 가정로 217 과학기술연합대학원대학교 나노계측과학과

File last modified: Jan. 10 2018