Characterization of TiO2-Based MISIM Ultraviolet Photodetectors by Ultrasonic Spray Pyrolysis

In this letter, non-vacuum ultrasonic spray pyrolysis deposition was used to grow Al2O3/TiO2 thin film as the metal-insulator-semiconductor-insulator-metal ultraviolet photodetector (MISIM UV PD). The anatase TiO2 with 400 degrees C annealing was used as the active layer of the UV PD. X-ray diffraction and Raman spectra were used to characterize the crystal phase of the TiO2. The Al2O3/TiO2 MISIM UV PD has lower dark current (similar to 57.2 pA), higher photoresponse (similar to 24.48 A/W), and higher detectivity (similar to 8.25 x 10(13) Jones), all of which were better than the TiO2 MSM UV PD. Similar device performance was obtained from the SiO2/TiO2 MISIM UV PD. The external quantum efficiency of the Al2O3/TiO2 and SiO2/TiO2 MISIM UV PDs was 8204% and 6840%. Such high external quantum efficiency results from the internal photoconductive gain and the interfacial trap controlled charge injection.