Device isolation of ultraviolet-detecting ZnO-based transistors using energetic B ions

We report on the fabrication of ultraviolet (UV)-detecting ZnO-based thin-film transistors (TFTs) and their isolation by energetic B ions. After deposition on a SiO₂/p⁺-Si substrate at 300°C by radio frequency (rf) sputtering, the ZnO layer was patterned with Al source/drain (S/D) contacts and a SiO_x window. Then energetic B ions with 30 and 55 keV were implanted onto the deposited structures for device isolation. Among the three samples of unimplanted, 30 keV-, and 55 keV-implanted devices, the 55 keV-implanted one displayed the least gate current leakage (∼100 pA). The ZnO-TFT isolated with 55 keV B also showed a field mobility of 0.7 cm ²/V s and on/off current ratio of more than ∼10⁴, respectively. Under 364 nm UV light of 0.2 mW/cm² and at zero volts of gate bias, the device exhibited a photo-to-dark current ratio of ∼5 × 103 with a temporal response of about 10 ms.