Application of transparent a-ITZO/Al2O3coupled MSIM diode into a photo-sensing switch

Abstract

We introduce a transparent diode that consists of a coupled junction of amorphous indium tin zinc oxide and Al2O3. In addition, the photo-sensing behavior under visible light was investigated. In the initial dark state, the diode exhibited maximum on current density of 10 A/cm2 and off current density of 10-9 A/cm2-10-10 A/cm2. Because of the extremely low off current level, it exhibited an excellent on/off ratio of 1010-1011. The light sensibility of the diode started from as low as 250 lux, and the off current density increased about three orders of magnitude under the exposure of 3000 lux. Such an off current density increase turned out to be mainly due to the short wavelength (400 nm) visible light, which has enough energy to generate photo-electrons from the valence band or deep level trap site to the conduction band. Meanwhile, a square pulse type dynamic light sensing test resulted in residual current at the dark state. The residual current was electrically removed by applying a forward bias, and the identical light sensing reproducibility was confirmed by repetitive trials.