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

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.