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TFET-Based Sensor Design for Healthcare Applications
Published in Balwinder Raj, Brij B. Gupta, Jeetendra Singh, Advanced Circuits and Systems for Healthcare and Security Applications, 2023
Tulika Chawla, Mamta Khosla, Balwinder Raj
Gas sensors particularly developed for human breath analysis are a reliable option for a fast and accurate detection of illnesses compared to existing conventional diagnosis procedures such as slow-through and intrusive blood tests. The shift in H2S, NH3, NO, and toluene trace species that are present in an exhaled breath may be utilized to detect halitosis, renal dysfunction, asthma, and lung cancer [15,91,92], correspondingly. Therefore, gas sensors need to be very sensitive for the purpose of an efficient biomedical diagnosis instrument. An ammonia gas sensing nanowire doping-less FET has been reported in [93]. In this gas sensor, IGZO is used as a channel material, which has superior mobility as compared to conventional amorphous semiconductor material. The mechanism behind the gas sensing is that variation in work-function of gate metal (cobalt, molybdenum) as some gas molecules react with a metal gate that causes a variation in Ioff, Ion and Vth parameters. These parameters are often taken into account as sensitivity parameters for NH3 gas detection. The schematic for nanowire doping-less TFET is shown in Figure 4.23 [93]. A comparison plot of On-current sensitivity w.r.t modulation in work function for different catalytic gate metal electrodes is shown in Figure 4.24 [93]. Similarly, Sonal et.al. proposed a vertical junction-less TFET-based gas sensor for the detection of NH3 gas [88].
Carbon Nanotube Transistors
Published in Changjian Zhou, Min Zhang, Cary Y. Yang, Nanocarbon Electronics, 2020
Min Zhang, Chunhui Du, Qiuyue Huang, Zhiqiang Liao, Yanyan Deng, Weihong Huang, Xiaofang Wang
For planar display and other non-silicon platforms, the conventional amorphous silicon (α-silicon) based electronics cannot satisfy the requirement of high frame rate due to the low carrier mobility [29] and poor stability [30, 31], and the application of polysilicon is limited by the processing cost and large-area uniformity. The commercialized indium gallium zinc oxide (IGZO) has a carrier mobility that is one order of magnitude higher than that of α-silicon [32], satisfying the requirement of medium quality display. However, it suffers from the instability to environment [33] and the exhaustion of rare-earth element. Moreover, both silicon and metal oxide have limitation for flexible electronics due to their brittle nature. Organic materials are widely used in flexible electronics, and all the components, including substrate, channel, electrodes, and dielectric, can be formed by polymers [18, 34]. The critical problems of organic material are the low mobility and the mobility degradation at a high gate voltage [35, 36]. Two-dimensional (2D) materials such as single-or few-layered graphene, black phosphorus [37, 38], and transition metal dichalcogenides (TMDs) [39] share common merits on quasi-transparency, in-planar electron transport, and mechanical flexibility, demonstrating a great potential for transparent and flexible nanoelectronics. However, many problems still exist ahead to be addressed, such as instability, harsh synthetic conditions, and low on/off current ratio (Ion/Ioff).
Flexible and Stretchable Thin-Film Transistors
Published in Muhammad Mustafa Hussain, Nazek El-Atab, Handbook of Flexible and Stretchable Electronics, 2019
Joseph B. Andrews, Jorge A. Cardenas, Aaron D. Franklin
Another more common metal-oxide used for TFTs is InGaZnO4 or IGZO. Similar to ZnO mentioned above, many IGZO based-devices are fabricated using vacuum-based deposition techniques (typically direct current [DC] sputtering), which limit the substrate size and fabrication throughput. However, vacuum processed IGZO films provide the highest performing option for TFTs with typical on/off ratios ranging from 105–109, mobilities ranging from 10–90 cm2/(V-s), and subthreshold swings as low as 100–300 mV/dec, depending on the quality of the dielectric [43,124–126]. Additionally, many metal-oxide films can be deposited from solution through spin-casting, which typically results in lower performing films, though this can be somewhat alleviated by sintering at high temperatures (>300°C), which in turn prevents fabrication on most flexible substrates. There are many emerging low-temperature processing methods with the potential to recover this compromise in performance through combustion synthesis or photochemical activation methods [123,127].
Oxide thin-film transistors based on i-line stepper process for high PPI displays
Published in Journal of Information Display, 2023
Ji-Min Park, Seong Cheol Jang, Seoung Min Lee, Min-Ho Kang, Kwun-Bum Chung, Hyun-Suk Kim
To fabricate the short-channel IGZO devices, a Si wafer with wet-thermally-grown 300-nm-thick SiOx was used as a substrate. Aluminum (Al) was deposited as the gate electrode using a sputtering system. A 300-nm-thick SiO2 film was subsequently formed by plasma-enhanced chemical vapor deposition (PECVD) as the gate dielectric. This was followed by depositing 30-nm-thick IGZO active layers via sputtering at room temperature using an IGZO target (In:Ga:Zn = 1:1:1 at%). The working pressure was fixed at 2 m Torr, with Ar and O2 gas flow rates at 50 and 5 sccm, respectively. Finally, a 150-nm-thick source and drain Al electrode were deposited by sputtering. Thermal annealing was conducted at 300°C for one hour in ambient air after completion of all deposition processes.
Progress of display performances: AR, VR, QLED, OLED, and TFT
Published in Journal of Information Display, 2019
Ho Jin Jang, Jun Yeob Lee, Jeonghun Kwak, Dukho Lee, Jae-Hyeung Park, Byoungho Lee, Yong Young Noh
To drive an OLED display, a charge carrier mobility of about 10–100 cm2/Vs is needed. Indium gallium zinc oxide (IGZO), a typical material of amphorous metal oxide TFTs, showed a mobility of about 10 cm2/Vs and was commercialized for OLED TVs by LG Display. For higher-resolution OLED display application, however, it is necessary to improve the mobility of metal oxide TFTs. Various metal oxide materials have been tried to obtain a mobility value higher than that of IGZO TFTs, but the stability has not yet reached the level of IGZO, so further studies are needed to commercialize such materials.
Recent progress in the development of backplane thin film transistors for information displays
Published in Journal of Information Display, 2021
Dongseob Ji, Jisu Jang, Joon Hui Park, Dasol Kim, You Seung Rim, Do Kyung Hwang, Yong-Young Noh
Indium gallium zinc oxide (IGZO), the prototypical amorphous metal oxide TFT, has µ ∼ 10 cm2·V−1·s−1. IGZO has been commercialized for OLED TVs. To increase the resolution and speed of OLED display applications, however, the carrier mobility of metal oxide must be increased further. Various metal oxide materials have been evaluated to obtain higher µ than IGZO TFTs can, but the materials have not achieved the stability, reliability, and large-area uniformity that IGZO provides, so further development is required before they can be commercialized.