Carrier imaging analyses of interfacial traps on gate insulator in organic field-effect transistors

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15432
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: The University of Tokyo
• Principal Investigator: Matsuoka Satoshi 東京大学, 大学院工学系研究科(工学部), 助教 (60826535)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 有機電界効果トランジスタ / キャリアイメージング / 絶縁膜界面 / 有機半導体

Outline of Final Research Achievements

Organic field-effect transistors (OFETs) attract the broad interests in application for next-generation electronics device, and the characteristics is affected by the interfacial state between the semiconductor and the dielectric layers. In this study, the interfacial carrier states are evaluated by means of the unique optical techniques, gate-modulation imaging, which allow us to detect and visualize the spatial distribution of charge carriers accumulated on the semiconductor-insulator interface. The measurements was conducted for the OFET devices composed of the single-crystal semiconductor layer and the insulator layer with several kinds of polymer dielectric. It was found that the electro-optic responses of OFETs are unexpectedly enhanced corresponding to the delocalization of accumulated carriers associated with the chemical functional groups on the insulator surface.

Free Research Field

有機エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究で用いたゲート変調イメージング法では、有機電界効果トランジスタのスイッチング性能を決める要因の一つである絶縁膜表面に蓄積した電荷キャリアを、最先端のカメラを用いて光学的に測定する。従来の電気的評価に比べて、性能律速要因が素子内部でどのように分布するかを判別することが可能となる。今回、半導体層内のキャリア密度に比例しない異常な光学応答を初めて観測し、有機光物性分野における新しい電気光学現象を見出すとともに、絶縁層に用いた誘電ポリマー材料が半導体層内に蓄積したキャリアの運動性に大きく影響することを明らかにした。