The field effect and nonlinear capacitance of a semiconductor layer with intrinsic conductivity

1986 ◽  
Vol 29 (7) ◽  
pp. 656-663
Author(s):  
Yu. A. Romanov ◽  
A. L. Chernov
2007 ◽  
Vol 124-126 ◽  
pp. 407-410
Author(s):  
Sang Chul Lim ◽  
Seong Hyun Kim ◽  
Gi Heon Kim ◽  
Jae Bon Koo ◽  
Jung Hun Lee ◽  
...  

We report the effects of instability with gate dielectrics of pentacene thin film transistors (OTFTs) inverter circuits. We used to the UV sensitive curable resin and poly-4-vinylphenol(PVP) by gate dielectrics. The inverter supply bias is VDD= -40 V. For a given dielectric thickness and applied voltage, pentacene OTFTs with inverter circuits measurements field effect mobility, on-off current ratio, Vth. The field effect mobility 0.03~0.07 cm2/Vs, and the threshold voltage is -3.3 V ~ -8.8 V. The on- and off-state currents ratio is about 103~106. From the OTFT device and inverter circuit measurement, we observed hysteresis behavior was caused by interface states of between the gate insulator and the pentacene semiconductor layer.


2007 ◽  
Vol 1029 ◽  
Author(s):  
Shun-Wei Liu ◽  
Jia-Cing Huang ◽  
Chih-Chien Lee ◽  
Chin-Ti Lee ◽  
Juen-Kai Wang

AbstractIn this report, we demonstrate that the performance and stability of pentacene top-contact field-effect transistor can be greatly improved with post-annealing treatment. After post-annealing at 90°C for 12 hours in nitrogen environment, the hole field-effect mobility of 0.3 cm2/Vs and the on/off current ratio of 107 were achieved, demonstrating 100% improvement in performance after the post-annealing treatment. The decay rate of drain current at constant gate and drain-source voltage was found to be decreased by more than 40%. The improved performance is attributed to the elimination of trapped holes and lattice defects in the organic semiconductor layer due to the post-annealing process.


2011 ◽  
Vol 10 (04n05) ◽  
pp. 891-898 ◽  
Author(s):  
RAVISHANKAR S. DUDHE ◽  
HARSHIL N. RAVAL ◽  
ANIL KUMAR ◽  
V. RAMGOPAL RAO

Organic semiconducting material based sensors have been used for various environmental applications. Organic field effect transistors (OFETs) also find their applications in explosive vapor detection and total ionizing radiation dose determination. OFETs using poly 3-hexylthiophene (P3HT), a p-type organic semiconductor material and CuII tetraphenylporphyrin ( CuTPP ) composite as their active material were investigated as sensors for detection of various nitro-based explosive vapors with greater than parts per billion sensitivity range. Significant changes, suitable for sensor response, were observed in ON current (Ion) and transconductance (gm) extracted from electrical characteristics of the OFET after exposure to vapors of various explosive compounds. However, a similar device response was not observed to strong oxidizing agents such as benzoquinone (BQ) and benzophenone (BP). Also, the use of organic semiconducting material sensors for determining total ionizing radiation dose was studied, wherein the conductivity of the material was measured as a function of total ionizing radiation dose. An organic semiconducting material resistor was exposed to γ-radiation and it was observed that the change in resistance was proportional to the ionizing radiation dose. Changes in various parameters extracted from electrical characteristics of the OFET after γ-radiation exposure resulted in an improved sensitivity. To protect the organic semiconductor layer from the degradation in the ambient the sensors were passivated with a thin layer of silicon nitride.


2016 ◽  
Vol 16 (4) ◽  
pp. 3277-3281
Author(s):  
Hirosato Monobe ◽  
Masaomi Kimoto ◽  
Yo Shimizu

In this study, we used a liquid crystalline (LC) semiconductor, 8TNAT8, solution (e.g., 0.1 wt% in toluene) for forming an organic semiconductor layer by solution casting method, and fabricated bottom-gate/bottom-contact type field effect transistors (FETs). These LC semiconductors show FET characteristic properties and have high carrier mobility of 0.01 cm2 V−1 s−1. We have investigated the surface morphology and the influence of temperature variation on LC FET properties across the phase transition from crystal to mesophase of a LC semiconductor, 8TNAT8. In the most cases, FET mobility was irreversibly decreased after temperature heat stress above the melting point of 8TNAT8, owing to the morphological change of LC layer.


2014 ◽  
Vol 14 (3) ◽  
pp. 152-160 ◽  
Author(s):  
Lina Rambausek ◽  
Els Bruneel ◽  
Isabel Van Driessche ◽  
Lieva Van Langenhove

Abstract The idea of wearable electronics automatically leads to the concept of integrating electronic functions on textile substrates. Since this substrate type implies certain challenges in comparison with their rigid electronic companions, it is of utmost importance to investigate the application of materials for generating the electronic functions on the textile substrate. Only when interaction of materials and textile substrate is fully understood, the electronic function can be generated on the textile without changing the textile’s properties, being flexible or stretchable. This research deals with the optimization of the dielectric layer in a fibrous organic field effect transistor (OFET). A transistor can act as an electrical switch in a circuit. In this work, the polyimide layer was dip-coated on a copper-coated polyester filament. After thoroughly investigating the process conditions, best results with minimal thickness and roughness at full insulation could be achieved at a dip-coating speed of 50 mm/min. The polyimide solution was optimal at 15w% and the choice for the solvent NMP was made. In this paper, details on the pre-treatment methods, choice of solvent and dip-coating speed and their effect on layer morphology and thickness, electrical properties and roughness are reported. Results show that the use of polyimide as a dielectric layer in the architecture of a fibrous OFET is promising. Further research deals with the application of the semiconductor layer within the mentioned architecture, to finally build an OFET on a filament for application in smart textiles.


The study aimed at the investigation and application of SnS thin film semiconductor as a channel layer semiconductor in the assembly of an electric double layer field effect transistor which is important for the achievement and development of novel device concepts, applications and tuning of physical properties of materials since the reported EDLFET and the modulation of electronic states have so far been realised on oxides, nitrides, carbon nanotubes and organic semiconductor but has been rarely reported for the chalcogenides. Honey was used as a gel like electrolytic gate dielectric to generate an enhanced electric field response over SnS semiconductor channel layer and due to its ability to produces high on-current and low voltage operation while forming an ionic gel-like solution similar to ionic gels which consist of ionic liguids. SnS gated honey Electric double layer field effect transistor was assembled using tin sulphide (SnS) thin film as semiconductor channel layer and honey as gate dielectric. The measured gate capacitance of honey using LCR meter was measured as 2.15 μF/ cm2 while the dielectric constant is 20.50. The semiconductor layer was deposited using Aerosol assisted chemical vapour deposition and annealed in open air at 250 on an etched region about the middle of a 4×4 mm FTO glass substrate with the source and drain electrode region defined by the etching and masking at the two ends of the substrate. Iridium was used as the gate electrode while a copper wire was masked to the source and drain region to create electrode contact. The Profilometry, X-ray diffraction, Scanning electron microscope, Energy dispersive X-ray spectroscopy, Hall Effect measurement and digital multimeters were used to characterise the device. The SnS thin film was found to be polycrystalline consisting of Sn and S elements with define grains, an optical band of 1.42 eV and of 0.4 μm thickness. The transistor operated with a p type channel conductivity in a depletion mode with a field effect mobility of 16.67 cm2/Vs, cut-off voltage of 1.6 V, Drain saturation current of1.35μA, a transconductance of -809.61 nA/V and a sub threshold slope of -1.6 Vdec-1 which is comparable to standard specifications in Electronics Data sheets. Positive gate bias results in a shift in the cut off voltage due to charge trapping in the channel/dielectric interface.


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1583 ◽  
Author(s):  
Damien Thuau ◽  
Katherine Begley ◽  
Rishat Dilmurat ◽  
Abduleziz Ablat ◽  
Guillaume Wantz ◽  
...  

Organic semiconductors (OSCs) are promising transducer materials when applied in organic field-effect transistors (OFETs) taking advantage of their electrical properties which highly depend on the morphology of the semiconducting film. In this work, the effects of OSC thickness (ranging from 5 to 15 nm) on the piezoresistive sensitivity of a high-performance p-type organic semiconductor, namely dinaphtho [2,3-b:2,3-f] thieno [3,2–b] thiophene (DNTT), were investigated. Critical thickness of 6 nm thin film DNTT, thickness corresponding to the appearance of charge carrier percolation paths in the material, was demonstrated to be highly sensitive to mechanical strain. Gauge factors (GFs) of 42 ± 5 and −31 ± 6 were measured from the variation of output currents of 6 nm thick DNTT-based OFETs engineered on top of polymer cantilevers in response to compressive and tensile strain, respectively. The relationship between the morphologies of the different thin films and their corresponding piezoresistive sensitivities was discussed.


2021 ◽  
Vol 2 (2) ◽  
pp. 60-71
Author(s):  
John Barron ◽  
Alec Pickett ◽  
James Glaser ◽  
Suchismita Guha

The use of high κ dielectrics lowers the operating voltage in organic field-effect transistors (FETs). Polymer ferroelectrics open the path not just for high κ values but allow processing of the dielectric films via electrical poling. Poled ferroelectric dielectrics in p-type organic FETs was seen to improve carrier mobility and reduce leakage current when compared to unpoled devices using the same dielectric. For n-type FETs, solution-processed ZnO films provide a viable low-cost option. UV–ozone-treated ZnO films was seen to improve the FET performance due to the filling of oxygen vacancies. P-type FETs were fabricated using the ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) as the dielectric along with a donor–acceptor polymer based on diketopyrrolopyrrole (DPP-DTT) as the semiconductor layer. The DPP-DTT FETs yield carrier mobilities upwards of 0.4 cm2/Vs and high on/off ratios when the PVDF-TrFE layer is electrically poled. For n-type FETs, UV–ozone-treated sol–gel ZnO films on SiO2 yield carrier mobilities of 10−2 cm2/Vs. DPP-DTT-based p- and ZnO-based n-type FETs were used in a complementary voltage inverter circuit, showing promising characteristic gain. A basic inverter model was used to simulate the inverter characteristics, using parameters from the individual FET characteristics.


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