Development of flexible functional devices by controlling oxygen-related defects in IGZO thin films prepared at low temperatures

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K15371
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 36010:Inorganic compounds and inorganic materials chemistry-related
• Research Institution: 防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群)
• Principal Investigator: Morimoto Takaaki 防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群), 電気情報学群, 准教授 (70754795)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 酸化物半導体 / ガスセンサー / ショットキー接触 / 溶液法

Outline of Final Research Achievements

A thin-film transistor (TFT) fabricated by coating a solution of the oxide semiconductor In-Ga-Zn-O (IGZO), which has recently been put into practical use, exhibits a drain current that is reduced to less than one thousandth of its original value when exposed to ozone at a concentration of 5 ppm, and can be reset to its original value by irradiating it with visible light. In other words, it has been found to function as an ozone gas sensor. Since the detection sensitivity is positively correlated with the amount of hydroxyl groups in the IGZO film, a reaction model has been proposed in which electrons supplied from the hydroxyl groups contribute to the reaction with ozone. In addition, it has been found that a gold/IGZO/gold stacked structure, in which current flows in only one direction, has the potential to function as a diode, because an ohmic contact is formed between the lower gold and IGZO, while a Schottky contact is formed between the upper gold and IGZO.

Free Research Field

電気電子工学

Academic Significance and Societal Importance of the Research Achievements

センサーやディスプレイ等を高分子フィルムや紙の上に搭載したフレキシブル半導体回路を低コストかつ単純な工程で可能な溶液法で作製するには、電子回路の基本素子であるトランジスタのみならず、センサーや電源など多様な素子もフレキシブル化する必要がある。本研究成果は、オゾンガスセンサーと電源の主要素子であるダイオードを溶液化されたIGZOを用いて作製する手法の確立につながるものであり、フレキシブルデバイスの作製に大いに貢献すると思われる。