Characterization of a 2D Electron Gas at the Interface of Atomic‐Layer Deposited Al2O3/ZnO Thin Films for a Field‐Effect Transistor. (4th December 2020)

• Record Type: Journal Article
• Authors: Lee, Hyun Jae; Moon, Taehwan; Hyun, Seung Dam; Kang, Sukin; Hwang, Cheol Seong
• Is Part Of: Advanced Electronic Materials. Volume 7:Number 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-04
• Subjects: 2D electron gas -- aluminum oxide -- atomic layer deposition -- field‐effect transistors -- zinc oxide; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.202000876
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: 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‐Al2 O3 ( 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(CH3 )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. Abstract : 2D electron gas (2DEG) at the interface of atomic‐layer deposited Al2 O3 (AO)/ZnO thin films and its application as a field‐effect‐transistor (FET) are characterized. The 2DEG at AO/ZnO shows sheet resistance of 2.7 × 10 4 Ω ▫ −1 and Hall mobility of 8.4 cm 2 V −1 s −1 with a confined thickness of 0.62 nm. The 2DEG FET exhibits threshold voltage of −2.4 V and on/off ratio of 9.4 × 10 6 .