High-Performance UV Detector Using Al-Doped ZnO Phototransistor Prepared by Initiated-CVD Doping Technique

• Published in: IEEE transactions on electron devices 2024-12, Vol.71 (12), p.7596-7601
• Main Authors: Baek, Jongsu, Kim, Heetae, Kim, Dongbin, Choi, Yoonho, Kim, Yongki, Yoon, Youngbin, Kim, Min Ju, Shin, Myunghun, Cho, Byung Jin
• Format: Article
• Language: English
• Subjects: Aluminum (Al)-doped zinc oxide(ZnO); Chemical vapor deposition; Doping; II-VI semiconductor materials; initiated chemical vapor deposition (iCVD); Logic gates; Low noise; oxygen vacancy defects; Photonic band gap; phototransistor (PT); Phototransistors; Polymers; Thin film transistors; Thin films; Threshold voltage; ultraviolet (UV); Ultraviolet detectors; UV-to-visible rejection ratio; X-ray scattering; Zinc; Zinc oxide; Zinc oxides
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2024.3481208

A novel doping technique with an initiated chemical vapor deposition (iCVD) process is applied to fabricate aluminum (Al)-doped zinc oxide (ZnO) channel thin-film ultraviolet (UV) phototransistor (PT). The iCVD doping technique can successfully introduce Al throughout the ZnO channel without any surface damage. The sub-bandgap states mainly due to oxygen vacancy (VO) defects in the ZnO channel are effectively suppressed by Al doping; the subthreshold swing (SS) of the PT has been reduced by more than half to 168 mV/dec and under negative gate bias illumination stress, the threshold voltage shift is reduced by about half to −2.03 V, which improves the reliability. For the UV detection, the Al-doped ZnO PT exhibits a high responsivity of 358.93 A \cdot W−1, an ultrahigh UV-to-visible rejection ratio of 4.81\times 10^{{6}} , a high detectivity ( {D} ^{\ast } ) of 1.68\times 10^{{15}} Jones, a low noise equivalent power (NEP) of 2.98\times 10^{-{18}} W \cdot Hz−1, and fast switching performance. The developed Al-doped ZnO PT can be used in low-cost and high-performed UV detection for various applications.