Light-bias interaction of zinc-tin oxide (ZTO) thin film transistor for charge-trapping memory application

In this work, we report the program-erase operation of a nonvolatile charge trapping memory base on a thin film transistor. The transistor is composed of an ultra-thin zinc tin oxide (ZTO) semiconductor layer and an Al
₂
O
₃
/Ni-nanocrystals/SiO
₂
dielectric stack. The threshold voltage (VTH), sub-threshold swing, ION/IOFF ratio of the as-fabricated device are 1.8 V, 0.40 V/decade and ~10
⁷
, respectively. By applying a gate voltage of 40 V for 1s, the VTH shifts positively and is named the programmed state. The programmed VTH shift can be back-shifted by applying a gate voltage of -10 V with monochromatic light source of wavelengths (405, 532, 635 nm), the erasing is most effective at wavelength of 635 nm. Subsequently, it is found that the programmed state can be expediently erased by applying a gate voltage of -10 V with a visible light illumination for 1 s. Erasing process can also be done by visible light illumination only, but is not as efficient. The light-erasable memory can be integrated into low power consumption display devices owing to its light-sensing switching characteristics.