Investigation of TiO2-Based MISIM Ultraviolet Photodetectors With Different Insulator Layer Thickness by Ultrasonic Spray Pyrolysis Deposition

Abstract

This work uses ultrasonic spray pyrolysis deposition to grow titanium dioxide and aluminum oxide (Al2O3) films, respectively, as an active layer and an insulator layer of the metal–insulator–semiconductor–insulator–metal (MISIM) photodetector (PD). 10-, 20-, and 30-nm-thick Al2O3 films were deposited and the $I$ – $V$ characteristics in the dark and under illumination were measured and investigated. The dark current was suppressed to 11.6 pA for the MISIM PD with the 30-nm Al2O3. In addition, the carrier transportation mechanisms of the dark current are analyzed. The photoresponsivity of the MISIM PD with the 10-nm Al2O3 was 8.22 A/W (at 10 V), which is much higher than 0.84 A/W of the metal-semiconductor–metal PD. The noise equivalent power and detectivity of the MISIM PD with the 10-nm Al2O3 were $2.28\times 10^{-10}$ W and $2.4\times 10^{9}$ Jones. The PDs showed a slight degradation when the ambient temperature was up to 450 K.