Electron Holography Studies of Cadmium Telluride (CdTe)

• Project/Area Number: 18K04247
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Okinawa Institute of Science and Technology Graduate University
• Principal Investigator: Cassidy Cathal 沖縄科学技術大学院大学, 量子波光学顕微鏡ユニット, スタッフサイエンティスト (40792156)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000); Fiscal Year 2020: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000); Fiscal Year 2019: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000); Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
• Keywords: holography / semiconductor / CdTe / electron holography / Electron holography / EELS / device / microscopy / electron

Outline of Final Research Achievements

The electron holography method can uniquely and quantitatively image the potential distribution in a semiconductor material at the nanoscale level. On the other hand, CdTe is considered to be extremely useful as a material for next-generation medical imaging detectors, but there is still much room for improvement in the characteristics of the detector. The main causes are the material defects of CdTe itself and the deterioration of electrical properties due to the semiconductor-metal junction interface. This project aims to elucidate the effects of CdTe defects by observing at the nanoscale level using electron holography, and to contribute to improving the characteristics of the CdTe detector.

Academic Significance and Societal Importance of the Research Achievements

We have measured intrinsic material parameters that were previously unknown. We have also clarified the underlying physics which defines mean free paths in off-axis holography. We have established a collaboration with a local CdTe semiconductor company to continue the research.

Research Products

• [Journal Article] Measurement and analysis of the mean free path governing high-energy electron scattering in CdTe, via off-axis electron holography (2021)
  • Author(s): Cathal Cassidy, Hidehito Adaniya, Tsumoru Shintake
  • Journal Title: Journal of Applied Physics Volume: 129 Issue: 5
  • DOI: 10.1063/5.0036989
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Electron microscopy research @ Shintake unit (OIST) (2020)
  • Author(s): Cathal Cassidy, Hidehito Adaniya, Martin Cheung, Masao Yamashita, Tsumoru Shintake
  • Organizer: OIST-Hitachi Joint Symposium (Hitachi Central Research laboratory "Kyousou no Mori", Tokyo).
• [Presentation] Electron holography studies of CdTe devices (2019)
  • Author(s): Cathal Cassidy, Hidehito Adaniya, Shinichiro Takeda, Tadayuki Takahashi, Tsumoru Shintake
  • Organizer: CCEM (McMaster University, Hamilton, Canada)
• [Presentation] Electron holography studies of next-generation medical imaging sensor materials (2019)
  • Author(s): Cathal Cassidy, Hidehito Adaniya, Tsumoru Shintake, S. Takeda, T. Takahashi, M. Ageishi, D. Morikawa, K. Tsuda, T. Akashi, H. Kasai, H. Shinada
  • Organizer: OIST-Ryudai Symposium: Medical Sciences: basic medical science to clinical medecine