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X-ray 조사에 의한 bottom gate a-IGZO TFT의 음의 문턱 전압 변화

Title
X-ray 조사에 의한 bottom gate a-IGZO TFT의 음의 문턱 전압 변화
Other Titles
Negative threshold voltage shift in bottom gate a-IGZO TFT under X-ray irradiation
Author
김동규
Alternative Author(s)
Dong-Gyu Kim
Advisor(s)
최덕균
Issue Date
2020-02
Publisher
한양대학교
Degree
Master
Abstract
This study investigated the effects of X-ray irradiation on the electrical characteristics of an amorphous In–Ga–Zn–O (a-IGZO) thin film transistor (TFT). The a-IGZO TFT showed a negative threshold voltage (VTH) shift of 2.3 V after 130 Gy X-ray irradiation. Based on spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS) analysis, it is found that the Fermi energy (EF) changes from 2.73 eV to 3.01 eV and that the sub-gap state of D1 and D2 changes near the conduction band minimum (CBM) of the a-IGZO film after X-ray irradiation. These results imply that the negative VTH shift after X-ray irradiation is related to the increase in electron concentration of the a-IGZO TFT active layer. The sources for electron generation during X-ray irradiation are oxygen vacancy ionization, hydrogen incorporation from ambient air to the active layer, and hydrogen state transition effect. Since these causes are reversible processes involving an activation energy, the negative VTH shift is recovered by thermal annealing.
URI
https://repository.hanyang.ac.kr/handle/20.500.11754/123515http://hanyang.dcollection.net/common/orgView/200000437150
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > MATERIALS SCIENCE & ENGINEERING(신소재공학과) > Theses (Master)
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