field effect mobility
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Author(s):  
Rogério Miranda Morais ◽  
Douglas Henrique Vieira ◽  
Maykel dos Santos Klem ◽  
Cristina Gaspar ◽  
Luis Pereira ◽  
...  

Abstract Printed electronics is a reputable research area that encourages the search for simple alternatives of manufacturing processes for low-cost, eco-friendly, and biodegradable electronic devices. Among these devices, electrolyte-gated transistors (EGTs) stand out due to their simple manufacturing process and architecture. Here we report the study of printed electrolyte-gated transistors with in-plane gate architecture (IPGT) based on zinc oxide nanoparticles (ZnO-NPs). The drain, source, and gate electrodes with two different W/L channel ratios were fabricated using a screen-printed carbon-based ink. We also produced a conventional top-gate transistor as a control device, using the same structure as the IPGT described above by adding an ITO strip positioned over the electrolyte as the top-gate electrode. The IPGT with W/L = 5 presented a high mobility of 7.1 cm2V-1s-1, while the W/L = 2.5 device exhibited a mobility of 3.7 cm2V-1s-1. We found that the measured field-effect mobility of the device can be affected by the high contact resistance from the carbon electrodes. This effect could be observed when the geometric parameters of the devices were changed. Furthermore, we also found that the IPGT with W/L = 5 exhibited better values for mobility and transconductance than the top-gate transistor, showing that the IPGTs setup is a good promise for cheap and printed transistors with performance comparable to standard top-gate transistors.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 187
Author(s):  
Taiki Kataoka ◽  
Yusaku Magari ◽  
Hisao Makino ◽  
Mamoru Furuta

We successfully demonstrated a transition from a metallic InOx film into a nondegenerate semiconductor InOx:H film. A hydrogen-doped amorphous InOx:H (a-InOx:H) film, which was deposited by sputtering in Ar, O2, and H2 gases, could be converted into a polycrystalline InOx:H (poly-InOx:H) film by low-temperature (250 °C) solid-phase crystallization (SPC). Hall mobility increased from 49.9 cm2V−1s−1 for an a-InOx:H film to 77.2 cm2V−1s−1 for a poly-InOx:H film. Furthermore, the carrier density of a poly-InOx:H film could be reduced by SPC in air to as low as 2.4 × 1017 cm−3, which was below the metal–insulator transition (MIT) threshold. The thin film transistor (TFT) with a metallic poly-InOx channel did not show any switching properties. In contrast, that with a 50 nm thick nondegenerate poly-InOx:H channel could be fully depleted by a gate electric field. For the InOx:H TFTs with a channel carrier density close to the MIT point, maximum and average field effect mobility (μFE) values of 125.7 and 84.7 cm2V−1s−1 were obtained, respectively. We believe that a nondegenerate poly-InOx:H film has great potential for boosting the μFE of oxide TFTs.


Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 2
Author(s):  
Doyeon Kim ◽  
Minho Yoon ◽  
Jiyoul Lee

Herein, we report the fabrications of high-performance polymer field-effect transistors (PFETs) with wire bar-coated semiconducting polymer film as an active layer. For an active semiconducting material of the PFETs, we employed cyclopentadithiophene-alt-benzothiadiazole (CDT-BTZ) that is a D-A-type-conjugated copolymer consisting of a repeated electron-donating unit and an electron-accepting unit, and the other two CDT-based D-A-type copolymer analogues are cyclopentadithiophene-alt-fluorinated-benzothiadiazole (CDT-FBTZ) and cyclopentadithiophene-alt-thiadiazolopyridine (CDT-PTZ). The linear field-effect mobility values obtained from the transfer curve of the PFETs fabricated with the spin-coating were 0.04 cm2/Vs, 0.16 cm2/Vs, and 0.31 cm2/Vs, for CDT-BTZ, CDT-FBTZ, and CDT-PTZ, respectively, while the mobility values measured from the PFETs with the wire bar-coated CDT-BTZ film, CDT-FBTZ film, and CDT-PTZ film were 0.16 cm2/Vs, 0.28 cm2/Vs, and 0.95 cm2/Vs, respectively, which are about 2 to 4 times higher values than those of the PFETs with spin-coated films. These results revealed that the aligned molecular chain is beneficial for the D-A-type semiconducting copolymer even though the charge transport in the D-A-type semiconducting copolymer is known to be less critical to the degree of disorder in film.


Author(s):  
Takuma Doi ◽  
Shigehisa Shibayama ◽  
Mitsuo Sakashita ◽  
Noriyuki Taoka ◽  
Mitsuaki Shimizu ◽  
...  

Abstract We investigated the effect of interface state density on the field-effect mobility (μ FE) of 4H-SiC counter-doped MOSFETs. We fabricated counter-doped MOSFETs with three types of gate oxides i.e., SiO2, Al2O3 formed via atomic layer deposition, and Al2O3 formed via metal layer oxidation (MLO). A maximum μ FE of 80 cm2/Vs was obtained for the MLO-Al2O3 FET, and this value was 60% larger than that of the SiO2 FET. In addition, we evaluated the electron mobility in the neutral channel (μ neutral) and the rate of increase in the free electron density in the neutral channel with respect to the gate voltage (dN neutral/dV G), which are factors determining μ FE. μ neutral depended only on the channel depth, independent of the type of gate oxide. In addition, dN neutral/dV G was significantly low in the SiO2 FET because of carrier trapping at the high density of interface states, whereas this effect was smaller in the Al2O3 FETs.


2021 ◽  
Vol 2 ◽  
Author(s):  
Oliver Lahr ◽  
Max Steudel ◽  
Holger von Wenckstern ◽  
Marius Grundmann

Due to their low-temperature processing capability and ionic bonding configuration, amorphous oxide semiconductors (AOS) are well suited for applications within future mechanically flexible electronics. Over the past couple of years, amorphous zinc tin oxide (ZTO) has been proposed as indium and gallium-free and thus more sustainable alternative to the widely deployed indium gallium zinc oxide (IGZO). The present study specifically focuses on the strain-dependence of elastic and electrical properties of amorphous zinc tin oxide thin-films sputtered at room temperature. Corresponding MESFETs have been compared regarding their operation stability under mechanical bending for radii ranging from 5 to 2 mm. Force-spectroscopic measurements yield a plastic deformation of ZTO as soon as the bending-induced strain exceeds 0.83 %. However, the electrical properties of ZTO determined by Hall effect measurements at room temperature are demonstrated to be unaffected by residual compressive and tensile strain up to 1.24 %. Even for the maximum investigated tensile strain of 1.26 %, the MESFETs exhibit a reasonably consistent performance in terms of current on/off ratios between six and seven orders of magnitude, a subthreshold swing around 350 mV/dec and a field-effect mobility as high as 7.5 cm2V−1s−1. Upon gradually subjecting the transistors to higher tensile strain, the channel conductivity steadily improves and consequently, the field-effect mobility increases by nearly 80 % while bending the devices around a radius of 2 mm. Further, a reversible threshold voltage shift of about −150 mV with increasing strain is observable. Overall, amorphous ZTO provides reasonably stable electrical properties and device performance for bending-induced tensile strain up to at least 1.26 % and thus represent a promising material of choice considering novel bendable and transparent electronics.


2021 ◽  
Author(s):  
Yuanwei Zhu ◽  
Wanlong Lu ◽  
Nan Qiao ◽  
Huize Cui ◽  
Zhipeng Hu ◽  
...  

Abstract Polymers with excellent dielectric and electret capabilities are crucial for energy storage films, organic electronics and environmental filtrations. Nanocomposites is an emerging effective method, but the characteristics of complicated preparation, poor uniformity and high cost restrict its massive and practical applications. Here, we propose a gradient copolymerization strategy with controllable micro-phase interfaces for dielectric capability modulation, and gradient ethylene-styrene copolymer (PESt) exhibits extraordinarily enhanced dielectric, electrical insulating and electret properties against polyethylene and polystyrene. PESt exhibits a dielectric energy density towards 23 J·cm− 3, far exceeding commercially applied polymers and is comparable to nano-composites. By applying PESt as electret layer in organic field-effect transistors, largely enhanced memory window, optimized stability and field-effect mobility over 27 cm2·V− 1·s− 1 are achieved. Finally, PESt electret is employed in environmental filtrations with 20% enhancement in filtration efficiency. The simplicity and processability of gradient copolymerization against nano-composite, further suggest its potential in designing high-performance dielectric/electret polymers.


Author(s):  
Xufang Zhang ◽  
Tsubasa Matsumoto ◽  
Satoshi Yamasaki ◽  
Christoph E. Nebel ◽  
Takao Inokuma ◽  
...  

AbstractThis article reviews the state of the art in inversion-type p-channel diamond MOSFETs. We successfully developed the world’s first inversion-channel homoepitaxial and heteroepitaxial diamond MOSFETs. We investigated the dependence of phosphorus concentration (NP) of the n-type body on field-effect mobility (μFE) and interface state density (Dit) for the inversion channel homoepitaxial diamond MOSFETs. With regard to the electrical properties of both the homoepitaxial and heteroepitaxial diamond MOSFETs, they suffer from low μFE and one main reason is high Dit. To improve the interface quality, we proposed a novel technique to form OH-termination by using H-diamond followed by wet annealing, instead of the previous OH-termination formed on O-diamond. We made precise interface characterization for diamond MOS capacitors by using the high-low C–V method and the conductance method, providing further insights into the trap properties at Al2O3/diamond interface, which would be beneficial for performance enhancement of the inversion-type p-channel diamond MOSFETs. Graphic abstract


Author(s):  
Milinda Wasala ◽  
Prasanna Patil ◽  
Sujoy Ghosh ◽  
Lincoln Weber ◽  
Sidong Lei ◽  
...  

Abstract Understanding and optimizing the properties of photoactive two-dimensional (2D) Van der Waals solids is crucial for developing optoelectronics applications. The main goal of this work is to present a detailed investigation of layer dependent photoconductive behavior of InSe based field-effect transistors (FETs). InSe based FETs with five different channel thicknesses (t, 20nm < t < 100nm) were investigated with a continuous laser source of λ = 658 nm (1.88 eV) over a wide range of illumination power (P) of 22.8 nW < P < 1.29 μW. All the devices studied showed signatures of photogating; however, our investigations suggest that the photoresponsivities are strongly dependent on the thickness of the conductive channel. A correlation between the field-effect mobility (µFE) values (as a function of channel thickness, t) and photoresponsivity (R) indicates that in general R increases with increasing µFE (decreasing t) and vice versa. Maximum responsivities of ∼ 7.84 A/W and ∼ 0.59 A/W were obtained the devices with t = 20nm and t = 100nm, respectively. These values could substantially increase under the application of a gate voltage. The structure-property correlation-based studies presented here indicate the possibility of tuning the optical properties of InSe based photo-FETs for a variety of applications related to photodetector and/or active layers in solar cells.


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