ZnO and its ternary alloy Mg x Zn 1Àx O (MZO) are promising wide-band-gap semiconductor materials well-suited to UV detection. The Mg content of MZO facilitates energy band gap engineering, enabling fabrication of UV photodetectors that can operate in the deep-UV region. Different types of UV photodetector based on ZnO have been reported, including photoconductive, Schottky, and transistor types. Transistor-based photodetectors have the advantage of being three-terminal devices, thus enabling biasing control and implementation in addressable arrays. In this paper we report an MZO thinfilm-transistor (TFT)-based UV photodetector. The device has a low dark current (2 9 10 À14 A) and an ON/OFF ratio of 10 11 . We show that by using a small amount of Mg (5%) in the MZO TFT we can substantially improve the photoresponse recovery time of the photodetector to 15 ms compared with 42 ms for a similar TFT with 0% Mg. We also observed a shift in the cutoff wavelength from 377.21 nm for the 0% Mg TFT photodetector down to 370.96 nm for the MZO TFT photodetector. We attribute the enhanced recovery time improvement of the MZO TFT UV photodetector to suppression of oxygen vacancies as a result of incorporation of the Mg in the MZO.

A ZnO-based flexible high voltage thin film transistor (f-HVTFT) is fabricated on a plastic substrate. The f-HVTFT shows a blocking voltage of 150 V, on-current of 170 μA, and off-current of 0.01 pA at a drain bias of 10 V. The maximum recoverable bending radius of the device reaches 11 mm, and the blocking voltage is larger than 120 V while it is under bending. The unique center-symmetric circular structure of the f-HVTFT is particularly useful to the wearable systems, which enable one to operate under bending from arbitrary directions. The ZnO-based f-HVTFT is a promising candidate to be used for power management of self-powered wearable electronic systems.

In this study, dynamic hot carrier effect in the MILC p-channel TFT device has been characterized by the unique struture. This novel structure is capable of spatially resolving the hot carrier effect and is highly sensitive to detect the defect-rich region. The dynamic hot carrier stress has been focused on the impacts of the frequency, the rise time and the fall time. In varied frequency stress condition, the degradation in the drain-sided monitor transistor (DMT) increases monotonically with increasing frequency, infering that more defects are generated by extra dynamic stress contribution in the drain side and degrade the characteristic of device. Under varied fall time stress condition, the oncurrent degradtion is severe with decreasing fall time due to the extra voltage drop during voltage switch. The final part is effect of rise time. While device switches, the large voltage drop exists in the junction between the channel and the drain, which resulted in anothor hot carrier degradation.