Ultrathin and Ultrasensitive Direct X‐ray Detector Based on Heterojunction Phototransistors

• Published in: Advanced materials (Weinheim) Vol. 33; no. 32; pp. e2101717 - n/a
• Main Authors: Gao, Yuanhong, Ge, Yongshuai, Wang, Xinwei, Liu, Jin, Liu, Wenquan, Cao, Yong, Gu, Kaichen, Guo, Zheng, Wei, Yu‐Ming, Zhou, Ni, Yu, De, Meng, Hong, Yu, Xue‐Feng, Zheng, Hairong, Huang, Wei, Li, Jia
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.08.2021; Wiley Blackwell (John Wiley & Sons)
• Subjects: Carrier density; Detectors; Energy conversion; Flexibility; heterojunction phototransistors; Heterojunctions; high sensitivity; Image resolution; Low noise; photoconductive gain; Photoconductors; Phototransistors; Scintillation counters; Sensors; Spatial resolution; ultrathin materials; X‐ray detectors
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202101717

Most contemporary X‐ray detectors adopt device structures with non/low‐gain energy conversion, such that a fairly thick X‐ray photoconductor or scintillator is required to generate sufficient X‐ray‐induced charges, and thus numerous merits for thin devices, such as mechanical flexibility and high spatial resolution, have to be compromised. This dilemma is overcome by adopting a new high‐gain device concept of a heterojunction X‐ray phototransistor. In contrast to conventional detectors, X‐ray phototransistors allow both electrical gating and photodoping for effective carrier‐density modulation, leading to high photoconductive gain and low noise. As a result, ultrahigh sensitivities of over 105 μC Gyair−1 cm−2 with low detection limit are achieved by just using an ≈50 nm thin photoconductor. The employment of ultrathin photoconductors also endows the detectors with superior flexibility and high imaging resolution. This concept offers great promise in realizing well‐balanced detection performance, mechanical flexibility, integration, and cost for next‐generation X‐ray detectors. An ultrathin and ultrasensitive direct X‐ray detector based on a heterojunction phototransistor is developed by taking advantage of high‐gain and gating‐modulation mechanisms. This unique device concept allows for a significant reduction in X‐ray photoconductor thickness while maintaining high sensitivity and low detection limit, which opens up new opportunities for developing high‐resolution, flexible, and low‐cost X‐ray direct detectors.