Study on performance and reliability improvements of CdTe/Si X-ray imaging detectors

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04619
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Niraula Madan 名古屋工業大学, 工学(系)研究科(研究院), 教授 (20345945)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 放射線検出器 / 医療診断 / CdTe / エピタキシャル成長層 / ヘテロ接合ダイオード / 暗電流 / 転位密度

Outline of Final Research Achievements

Investigations were performed to improve the performance of a heterojunction diode-type detector fabricated by using metalorganic vapor phase epitaxy grown CdTe layer on a Si substrate. Efforts were made on the detector dark current reduction and crystal quality improvements of the CdTe layers. A strong dependence was found between the detector dark currents and the CdTe epilayer’s dislocation densities, which severely degrade the detector performance. Techniques for the dislocation density reduction as well as growth of a high-quality thick grown layer were established. Using this new technique, improvement of the detector performance was confirmed.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

Si基板上に成長したCdTe厚膜単結晶を用いて検出器を製作することにより、成長層の厚さや電気特性の精密な制御、さらに成長層の多層化も可能となる。これにより検出器設計の自由度が大きくなり、高性能かつ安定性も高い検出器の実現が見込める。さらに大口径Si基板上の成長層を用いることにより検出器の高集積化や大面積化、低価格化が見込める。これにより、医療分野では診断精度の向上と被爆量の低減に大きな貢献が期待できる。