Zinc Oxide Thin Film Transistors: Advances, Challenges and Future Trends

This paper presents a review on recent developments and future trends in zinc oxide thin film transistors (ZnO TFTs) together with challenges involved in this technology. It highlights ZnO TFT as next generation choice over other available thin film transistor technology namely a – Si: H (amorphous hydrogenated silicon), poly-Si (polycrystalline silicon) and OTFT (organic thin film transistor). This paper also provides a comparative analysis of various TFTs on the basis of performance parameters. Effect of high –k dielectrics, grain boundaries, trap densities, and threshold voltage shift on the performance of ZnO TFT is also explained

Intrinsically stretchable and transparent thin-film transistors based on printable silver nanowires, carbon nanotubes and an elastomeric dielectric.

Thin-film field-effect transistor is a fundamental component behind various mordern electronics. The development of stretchable electronics poses fundamental challenges in developing new electronic materials for stretchable thin-film transistors that are mechanically compliant and solution processable. Here we report the fabrication of transparent thin-film transistors that behave like an elastomer film. The entire fabrication is carried out by solution-based techniques, and the resulting devices exhibit a mobility of ∼30 cm(2) V(-1) s(-1), on/off ratio of 10(3)-10(4), switching current >100 μA, transconductance >50 μS and relative low operating voltages. The devices can be stretched by up to 50% strain and subjected to 500 cycles of repeated stretching to 20% strain without significant loss in electrical property. The thin-film transistors are also used to drive organic light-emitting diodes. The approach and results represent an important progress toward the development of stretchable active-matrix displays

On the transconductance of polysilicon thin film transistors

In order to achieve both driver and display capability for a number of display devices, TFT has attracted attention, model calculations are therefore presented for the grain boundary barrier height, in a polysilicon TFT considering the charge neutrality between the intrinsic free carriers and the grain boundary trap states. The formation of the potential barrier at a grain boundary is considered due to the trapping of carriers at the localized grain boundary trap states. The trapped charges, influenced by the gate bias voltage and the trapping states density, in turn, have been taken to deplete free carriers near the grain boundary in a device such as polysilicon TFT. The present predictions reveal that the barrier height diversely depends on the gate source voltage (VGS) of a TFT along with other crystal parameter. Finally to obtain the transconductance, the contributions of transverse and longitudinal grain boundary resistances are incorporated in the I-V characteristics of a TFT. For all values of grain size, the transconductance of the device is seen to increase initially with the gate voltage (VGS) which finally appears to be saturated. The dependence of the transconductance on grain size and drain voltage has been thoroughly explored. Good agreement with experimental results is achieved. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2299

All-Inkjet Printed Organic Thin-Film Transistors with and without Photo-Sensitivity to Visible Lights

Printable organic thin-film transistors have enabled flexible low-cost electronics, which has the potential for a lot of emerging electronic applications. Despite the excellent dark performance of advanced all-inkjet printed organic thin-film transistors, their photoresponse is less explored and needs to be investigated, especially photoresponse to visible lights that human beings can see and are most familiar with. Importantly, for electronics integration, both devices with and without photo-sensitivity to visible light are important, for photo-detecting and signal processing, respectively. In this study, two organic semiconductor materials are used in all-inkjet printed organic thin-film transistors, namely 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS-pentacene). By characterizing devices under optical exposure with wavelengths from 400 to 800 nm, photocurrents and threshold voltage shifts of the devices are extracted. The fabricated C8-BTBT organic thin-film transistors do not exhibit noticeable photo-sensitivity to visible light, whereas the TIPS-pentacene devices demonstrate significant photoresponse to visible lights, with photocurrents in nano- to micro-ampere levels and threshold voltage shifts of hundreds of millivolts to several volts depending on the photon energy of lights under the same intensity. The TIPS-pentacene devices demonstrated reproducible characteristics before and after light exposure. In addition, the responsivity and sensitivity of the devices were characterized with a decent responsivity of 55.9 mA/W. The photoresponse mechanisms are explained with ultraviolet−visible (UV−vis) adsorption spectroscopy measurements and extracted optical bandgaps of the two semiconductors. This study shows both printed organic transistors with and without photo-sensitivity can be fabricated with the same device structure and fabrication process at low cost, which opens the new possibility of using printed organic thin-film transistors for integrated optoelectronic applications

Dielectric breakdown II: Related projects at the University of Twente

In this paper an overview is given of the related activities in our group of the University of Twente. These are on thin film transistors with the inherent difficulty of making a gate dielectric at low temperature, on thin dielectrics for EEPROM devices with well-known requirements with respect to charge retention and endurance and, finally, on thin film diodes in displays with unexpected breakdown properties