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1.
In this paper, it was demonstrated that pentacene thin-film transistors (TFTs) were fabricated with an organic adhesion layer between an organic semiconductor and a gate insulator. In order to form polymeric film as an adhesion layer, a vapor deposition polymerization (VDP) process was introduced to substitute for the usual spin-coating process. Field effect mobility, threshold voltage, and on/off current ratio in pentacene TFTs with a 15 nm thick organic adhesion layer were about 0.4 cm2/Vs, -1 V, and 10(6), respectively. We also demonstrated that threshold voltage strongly depends on the stress time when a gate voltage has been applied for bias stress test. We suggest that a polyimide adhesion layer fabricated by the VDP method can be applied to realize organic TFTs with long-term stability because of lower threshold voltage shifts due to reduced charge trapping at the interface between the pentacene semiconductor and the polyimide layer.  相似文献   

2.
This paper describes the fabrication of pentacene thin-film transistors (TFTs) with an organic/inorganic hybrid gate dielectric, consisting of cross-linked poly(4-vinylphenol) (PVP) and Bi5Nb3O15. A 300-nm-thick Bi5Nb3O15 dielectric film, grown at room temperature, exhibits a high dielectric constant (high-k) value of 40 but has an undesirable interface with organic semiconductors (OSC). To form better interfaces with OSC, a cross-linked PVP dielectric was stacked on the Bi5Nb3O15 dielectric. It is shown that, with the introduction of a hybrid dielectric, our devices not only can be operated at a low voltage (- -5 V) but also have improved electrical characteristics and photoresponse, including a field-effect mobility of 0.72 cm2/V x s, current sub-threshold slopes of 0.29 V/decade, and a photoresponse of 4.84 at a gate bias V(G) = 0 V under 100 mW/cm2 AM 1.5 illumination.  相似文献   

3.
In this research, we reported on the fabrication of top-contact amorphous-indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) with an organic buffer layer between inorganic gate dielectric and active layer in order to improve the electrical properties of devices. By inserting an organic buffer layer, it was possible to make an affirmation of the improvements in the electrical characteristics of a-IGZO TFTs such as subthreshold slope (SS), on/off current ratio (I(ON/OFF)), off-state current, and saturation field-effect mobility (muFE). The a-IGZO TFTs with the cross-linked polyvinyl alcohol (c-PVA) buffer layer exhibited the pronounced improvements of the muFE (17.4 cm2/Vs), SS (0.9 V/decade), and I(ON/OFF) (8.9 x 10(6)).  相似文献   

4.
The flourishing metal-oxide high-k dielectric materials have been regarded as the vital components of low voltage operated flexible transparent electronic devices.We herein report that ytterbium oxide(Yb2O3)and ZnSnO(ZTO)thin films were firstly integrated into ZTO-based thin film transistors(TFTs)with superior performance.Results have indicated that the 500℃-annealed ZTO/Yb2O3 TFTs possess the large saturation mobility of 9.1 cm2 V-1 S-1 and the high on/off current ratio of 2.15×107,which even surpass those of reported In-based TFTs.The deteriorative electrical properties in the aging process can be attributed to the carrier capture mechanism.However,the 460℃-processed TFTs demonstrate a tenfold increase in saturated mobility and an increase in on/off current ratio after 10 days aging.The inspiring electrical properties are attributed to the diffusion-activated carrier enhancement mechanism and electrons donor role of water molecular,which introduces a facile method to boost the device per-formance at lower processing temperatures.The neglected threshold voltage variations of 0.06 V and-0.2 V have been detected after bias stability experiments.The superior bias stability can be attributed to the charge delay effect induced by the continuous electric field.Meanwhile,the ultrahigh on/off cur-rent ratio of 1.1 x 107 and the recoverable transferring performance have verified the aging-activated mechanism.To confirm its potential application in digital circuits,a resistor-loaded inverter with gain of 5.6 has been constructed and good dynamic response behavior have been detected at a low voltage of 2 V.As a result,it can be concluded that the high temperature annealing TFTs need immediate encapsula-tion,while the performance of the lower temperature processing samples can be optimized after aging treatment,indicating the potential prospect in low power consumption large-scale flexible transparent devices.  相似文献   

5.
Amorphous indium zinc oxide (a-IZO) thin-film transistors (TFTs) with bottom- and top-gate structures were fabricated at room temperature by direct current (DC) magnetron sputter in this research. High dielectric constant (κ) hafnium oxide (HfO2) films and a-IZO were deposited for the gate insulator and the semiconducting channel under a mixture of ambient argon and oxygen gas, respectively. The bottom-gate TFTs showed good TFT characteristics, but the top-gate TFTs did not display the same characteristics as the bottom-gate TFTs despite undergoing the same process of sputtering with identical conditions. The electrical characteristics of the top-gate a-IZO TFTs exhibited strong relationships with sputtering power as gate dielectric layer deposition in this study. The ion bombardment and incorporation of sputtering ions damaged the interface between the active layer and the gate insulator in top-gate TFTs. Hence, the sputtering power was reduced to decrease damage while depositing HfO2 films. When using 50 W DC magnetron sputtering, the top-gate a-IZO TFTs showed the following results: a saturation mobility of 5.62 cm2/V-s; an on/off current ratio of 1 × 105; a sub-threshold swing (SS) of 0.64 V/decade; and a threshold voltage (Vth) of 2.86 V.  相似文献   

6.
We have fabricated the flexible pentacene based organic thin film transistors (OTFTs) with formulated poly[4-vinylphenol] (PVP) gate dielectrics treated by CF4/O2 plasma on poly[ethersulfones] (PES) substrate. The solution of gate dielectrics is made by adding methylated poly[melamine-co-formaldehyde] (MMF) to PVP. The PVP gate dielectric layer was cross linked at 90 degrees under UV ozone exposure. Source/drain electrodes are formed by micro contact printing (MCP) method using nano particle silver ink for the purposes of low cost and high throughput. The optimized OTFT shows the device performance with field effect mobility of the 0.88 cm2/V s, subthreshold slope of 2.2 V/decade, and on/off current ratios of 1.8 x 10(-6) at -40 V gate bias. We found that hydrophobic PVP gate dielectric surface can influence on the initial film morphologies of pentacene making dense, which is more important for high performance OTFTs than large grain size. Moreover, hydrophobic gate dielelctric surface reduces voids and -OH groups that interrupt the carrier transport in OTFTs.  相似文献   

7.
Jong Hoon Kim 《Thin solid films》2008,516(7):1529-1532
Coplanar type transparent thin film transistors (TFTs) have been fabricated on the glass substrates. The devices consist of intrinsic ZnO, Ga doped ZnO (GZO), and amorphous HfO2 for the semiconductor active channel layer, electrode, and gate insulator, respectively. GZO and HfO2 layers were prepared by using a pulsed laser deposition (PLD) and intrinsic ZnO layers were fabricated by using an rf-magnetron sputtering. The transparent TFT exhibits n-channel, enhancement mode behavior. The field effect mobility, threshold voltage, and a drain current on-to-off ratio were measured to be 14.7 cm2/Vs, 2 V, and 105, respectively. High optical transmittance (> 85%) in visible region makes ZnO TFTs attractive for transparent electronics.  相似文献   

8.
Transparent ZnO thin film transistors (ZnO–TFTs) with different structures and dielectric layers were fabricated by rf magnetron sputtering. The PbTiO3, AlO x , SiN x and SiO x films were attempted to serve as the gate dielectric layers in the devices, respectively, and XRD was employed to investigate the crystal structure of ZnO films deposited on these dielectric layers. The optical properties of transparent TFTs were measured and revealed the average transmittance ranged from 60 to 80% in the visible part of the spectrum. Electrical measurement shows the properties of the ZnO–TFTs have great relations with the device structure. The bottom-gate TFTs have better behaviors than top-gate ones with the mobility, threshold voltage and the current on/off ratio of 18.4 cm2 V−1 s−1, −0.7 V and 104, respectively. The electrical difference of the devices may be due to different character of the interface between the channel and dielectric layers.  相似文献   

9.
In this article, we report the fabrication of organic field-effect transistors using self-assembled SiO2 as a gate dielectric material and pentacene as a semiconductor. The dielectric layer was self-assembled with 10 layers of SiO2 nanoparticles 45 nm in diameter, and its breakdown field was larger than 0.57 MV/cm. Being a low-cost and low-temperature process, the layer-by-layer self-assembly is particularly suitable for organic field-effect transistor fabrication. The pentacene was thermally evaporated on the substrate under high vacuum at the room temperature. The fabricated transistor has a threshold voltage of 0.3 V, field-effect mobility of 0.05 cm2/Vs, and slope of 1.4 V/decade.  相似文献   

10.
We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.  相似文献   

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