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Characterization of a 2D Electron Gas at the Interface of Atomic‐Layer Deposited Al 2 O 3 /ZnO Thin Films for a Field‐Effect Transistor
Author(s) -
Lee Hyun Jae,
Moon Taehwan,
Hyun Seung Dam,
Kang Sukin,
Hwang Cheol Seong
Publication year - 2021
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.202000876
Subject(s) - materials science , amorphous solid , substrate (aquarium) , x ray photoelectron spectroscopy , wurtzite crystal structure , atomic layer deposition , layer (electronics) , optoelectronics , hall effect , fermi gas , thin film , field effect transistor , electron mobility , transistor , thin film transistor , analytical chemistry (journal) , nanotechnology , electron , electrical resistivity and conductivity , crystallography , chemical engineering , zinc , voltage , electrical engineering , oceanography , chemistry , engineering , quantum mechanics , physics , chromatography , metallurgy , geology
The 2D electron gas (2DEG) phenomenon that occurs at the amorphous thin film hetero‐oxide interface attracts great attention since it can avoid the use of a single‐crystal oxide substrate. In this study, the analysis of 2DEG at the interface of amorphous‐Al 2 O 3 ( a ‐AO)/ZnO is conducted using ZnO as the bottom substrate, where both the oxide films are grown by atomic layer deposition. Having used Al(CH 3 ) 3 as the Al‐precursor for the a ‐AO film growth on the previously grown ZnO film, its strong reducing power induces the 2DEG formation at the interface. As a result of the Hall measurement, the 2DEG at the a ‐AO/ZnO interface shows sheet resistance of 2.7 × 10 4 Ω ▫ −1 and Hall mobility of 8.4 cm 2 V −1 s −1 . Using angle‐resolved X‐ray photoelectron spectroscopy, the thickness of the 2DEG layer is calculated as 0.62 nm, which is ≈120% of the c‐axis of the wurtzite ZnO unit cell. The field‐effect transistor fabricated exhibits a threshold voltage of −2.4 V, sub‐threshold swing of 0.33 V dec −1 , and on/off ratio of 9.4 × 10 6 , which significantly outperforms similar devices from previous works. The outstanding operation of 2DEG at the interface of AO/ZnO as a channel presents a possibility for application to a 2D‐based integrated circuit.