High-Performance Thin-Film Transistors of Quaternary Indium-Zinc-Tin Oxide Films Grown by Atomic Layer Deposition

In Hwan Baek, Jung Joon Pyeon, Seong Ho Han, Ga Yeon Lee, Byung Joon Choi, Jeong Hwan Han, Taek Mo Chung, Cheol Seong Hwang, Seong Keun Kim

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

A new deposition technique is required to grow the active oxide semiconductor layer for emerging oxide electronics beyond the conventional sputtering technique. Atomic layer deposition (ALD) has the benefits of versatile composition control, low defect density in films, and conformal growth over a complex structure, which can hardly be obtained with sputtering. This study demonstrates the feasibility of growing amorphous In-Zn-Sn-O (a-IZTO) through ALD for oxide thin-film transistor (TFT) applications. In the ALD of the a-IZTO film, the growth behavior indicates that there exists a growth correlation between the precursor molecules and the film surface where the ALD reaction occurs. This provides a detailed understanding of the ALD process that is required for precise composition control. The a-IZTO film with In/Zn/Sn = 10:70:20 was chosen for high-performance TFTs, among other compositions, regarding the field-effect mobility (μ FE ), turn-on voltage (V on ), and subthreshold swing (SS) voltage. The optimized TFT device with the a-IZTO film thickness of 8 nm revealed a high performance with a μ FE of 22 cm 2 V -1 s -1 , V on of 0.8 V, and SS of 0.15 V dec -1 after annealing at 400 °C for 30 min. Furthermore, an emerging device such as a vertical channel TFT was demonstrated. Thus, the a-IZTO ALD process could offer promising opportunities for a variety of emerging oxide electronics beyond planar TFTs.

Original languageEnglish
Pages (from-to)14892-14901
Number of pages10
JournalACS Applied Materials and Interfaces
Volume11
Issue number16
DOIs
StatePublished - 21 Feb 2019

Keywords

  • amorphous oxide
  • atomic layer deposition
  • In-Zn-Sn-O
  • thin film transistor
  • vertical transistor

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