Interface optimization of free-standing CdZnTe films for solar-blind ultraviolet detection: Substrate dependence

• Published in: Vacuum 2021-11, Vol.193, p.110484, Article 110484
• Main Authors: Chen, Rizhi, Shen, Yue, Li, Tuoshi, Huang, Jian, Gu, Feng, Liang, Xiaoyan, Cao, Meng, Wang, Linjun, Min, Jiahua
• Format: Article
• Language: English
• Subjects: CdZnTe thick Films; Defect states; Free-standing; Interface; Substrates; Thermal conductivity
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2021.110484

CdZnTe (CZT) thick films were deposited on AlN/Si, Si and glass substrates via close-spaced sublimation (CSS), and separated from substrates by ultrasonic method to obtain free-standing structures. Au electrodes were prepared on the interfaces of free-standing CZT films to realize MSM structural photodetectors. The effects of substrates on the structure, morphology, defect and photoelectric properties of interfaces of CZT films were investigated using XRD, SEM, HRTEM, XPS, PICTS and I–V characteristics. The results strongly suggest that AlN/Si substrates can facilitate the nucleation of CZT films and insure rapid lateral epitaxy, thus improving the morphology, crystallinity and carrier transport properties of CZT films at the interface, which is related to the highest thermal conductivity of AlN. In particular, PICTS analysis was used to study the defect states of CZT films for the first time, which indicates that AlN/Si substrates can help to reduce the deep-level defects of interfaces of CZT films. Compared with that of Si and glass substrates, CZT films detached from AlN/Si substrates show the highest μτ value (1.53 × 10−3 cm2/V), Iphoto/Idark ratio (258), responsivity (48.6 mA/W) and detectivity (8.38 × 1011 Jones) under 254 nm UV light illumination, informing the feasibility for solar-blind UV detection applications. •High quality CdZnTe thick films were deposited on AlN/Si, Si and glass substrates via CSS process.•A peel-off method was used to study the effect of substrate on the interfacial properities of CdZnTe thick films.•PICTS method was applied to investigate the deep-level defects of CdZnTe thick films at the interface.•AlN/Si substrate with high thermal conductivity is helpful to optimize the interfacial performance of CdZnTe thick films.