TWI453964B - Organic thin film transistor - Google Patents

Description

Organic thin film transistor

This invention relates to a transistor, and more particularly to an organic thin film transistor for gas sensing.

A gas sensor is a device (electronic nose) that converts the detected gas concentration into an electrical signal (such as voltage, current, and resistance) to detect/detect gas concentration. Gas sensors can be used to detect flammable gases or toxic gases, so they can be used in home safety, industrial safety, environmental pollution prevention, process control, road safety (drinking), food industry, and medical fields (eg, diabetes, lung cancer, Uremia, chronic hepatitis, cirrhosis, liver failure, renal failure, periodontal disease, detection/monitoring of diseases such as Helicobacter pylori infection (stomach ulcer), etc. There are quite a variety of gas sensors, including, for example, a catalytic combustion gas sensor, an electrochemical gas sensor, and a semiconductor-adsorbed gas sensor (semiconductor-absorbing). Gas sensor) and optical gas sensor.

Catalytic combustion gas sensor is the simplest gas sensor. Although it is not susceptible to temperature and humidity, it has poor sensitivity, poor selectivity, slow response time and easy electrode contamination. . Electrochemical gas sensors (such as liquid electrolyte type, solid electrolyte type, solid polymer electrolyte type), although having good sensitivity and selectivity, are difficult to manufacture, expensive, and often require recalibration. In addition, the liquid electrolyte has the disadvantages of corrosion and leakage, and the solid electrolyte type sensor is inconvenient to use and has the disadvantages of high operating temperature and easy contamination. The semiconductor adsorption type gas sensor includes, for example, a metal oxide semiconductor type (using materials such as SnO ₂ , ZnO, WO ₃ , TiO ₂ , In ₂ O ₃ , Fe ₂ O ₃ , ZrO ₂ , ITO, CuO, etc.), an organic metal Semiconductor type (using materials such as organic metal complexes) and conductive polymer type (using poly-para-phenylene (PPP), polythiophene (PT), polyaniline (polyaniline) , PANI) and other materials). For example, Chinese Patent No. 101819176A discloses a resistive gas sensor using CuO; Japanese Patent No. 101435795A discloses a resistive gas sensor using In ₂ O ₃ , SnO ₂ , ZnO; Liu, CJ, SY Wang, JC Hsieh and YH Ju, "Gas Sensing Properties of Vacuum-deposited Titanyl Phthalocyanine Film", Sensors and Actuators, B65 (2000), p371-374. discloses a resistive gas sensor using an organometallic complex. The semiconductor adsorption type gas sensing device has the advantages of good heat resistance, good corrosion resistance, simple preparation, low production cost, and the like, but the operating temperature is high, the response rate is slow, and the gas sensors have only a single parameter (resistance). It is not ideal in terms of sensitivity and selectivity. Compared with the above, the optical gas sensor can be operated not only at room temperature, but also in terms of sensitivity, selectivity and response rate. However, it is expensive, bulky and susceptible to temperature and humidity interference. .

In recent years, organic thin film transistors (OTFTs) composed of organic materials as active materials of field effect transistors have received increasing attention due to their advantages of low process temperature and low cost. The three-terminal field effect transistor can be used to fabricate a multi-parameter gas sensor, which is combined with an organic material to form an organic thin film transistor, which greatly enhances its selectivity. Xu Tingjun has revealed the study of pentaphenylcycline organic thin film transistors made of polyvinylphenol and polyvinylphenol-polymethyl methacrylate copolymer dielectric layers, and H. Touda, Hi. Tada, and K. Matsushige, "Evaluation of Carrier Mobility of Phthalocyanine Films in NH3 and NO2 Gas Atmosphere by Field Effect Measurement," Molecular Crystals and Liquid Crystals, Vol. 327, pp. 287-290, 1999. Uncovering an organic thin film transistor using a metal complex . The transistors can be gas-sensed at room temperature, but the sensitivity is still not high enough and the response rate is not fast enough.

Therefore, there is still a need for an organic thin film transistor which can be applied to a sensor with high sensitivity, high selectivity, fast response rate, low cost, high stability, and long service life. At the same time, products that meet the trend of miniaturization and portability are also needed.

In view of the lack of prior art, the present invention provides an organic thin film transistor having the advantages of low operating temperature, high sensitivity, high selectivity, fast response rate, and the like, which meets practical needs.

The invention provides an organic thin film transistor comprising: a gate; a source; a drain; a dielectric film formed on the gate; and an organic semiconductor layer formed on the dielectric film. The dielectric film includes a gate insulating layer to separate the gate and the organic semiconductor layer, and the organic semiconductor layer has at least one trench, and the trench is located between the source and the drain.

According to an embodiment of the invention, the organic semiconductor layer has 1 to 4 trenches.

According to a specific embodiment of the invention, the organic semiconductor layer comprises a titanium oxide phthalocyanine film.

According to an embodiment of the invention, the dielectric film comprises a gate insulating layer and a Self Assembly Monolayer (SAM). According to an embodiment of the invention, the gate insulating layer has a thickness of 20 to 1000 nanometers (nm). According to a specific embodiment of the invention, the Self Assembly Monolayer (SAM) contains octadecyltrimethoxydecane (OTMS) and/or octadecyltrichlorodecane (OTS).

In some aspects of the invention, the organic thin film transistor includes a substrate. According to an embodiment of the invention, the substrate is a germanium substrate.

The present invention further provides a gas sensor having an organic thin film transistor, comprising: a gate; a source; a drain; a dielectric film formed on the gate; and a dielectric film formed on the dielectric film And an organic semiconductor layer, wherein the organic semiconductor layer has at least one trench, and the trench is located between the source and the drain. According to an embodiment of the invention, the organic semiconductor layer has 1 to 4 trenches.

The organic thin film transistor of the invention has the advantages of high sensitivity, high selectivity, fast response rate, low cost, high stability, low operating temperature, and the like, and can be applied to gas sensing (including, for example, oxidizing gas and reducing gas). ). The sensor manufactured by using the organic thin film transistor of the present invention has the advantages of miniaturization and portability, and is therefore highly practical.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can understand the advantages and advantages of the present invention. The present invention may be embodied or applied in various other specific embodiments. The details of the present invention can be variously modified and changed without departing from the spirit and scope of the invention.

The singular <RTI ID=0.0>"1" </ RTI> </ RTI> and <RTIgt;

The term "or" as used in the specification and the scope of the appended claims generally includes the meaning of "and/or" unless otherwise indicated.

The invention will be more specifically described by the examples, but these examples are not intended to limit the scope of the invention.

According to the present invention, the organic thin film transistor mainly includes a gate, a source, a drain, a dielectric film, and an organic semiconductor layer.

The conductive material which can be used to form the gate, source, and drain of the present invention is not particularly limited. Examples of conductive materials include, but are not limited to, gold, nickel, chromium, silver, copper, aluminum, platinum, tin, palladium, iridium, lead, iron, lanthanum, indium, zinc, magnesium, lanthanum, cerium, lanthanum, tungsten. , molybdenum, lithium, strontium, sodium, potassium, calcium, etc., and alloys thereof; metal oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), ZnO, and SnO ₂ ; single crystal germanium, polycrystalline germanium , amorphous germanium, carbon black, graphite, fullerene, glassy carbon, carbon nanotubes, polyacetylene, polyparaphenylene, polyaniline, polythiophene, polypyrrole, polyphenylene, Polythene styrene vinylene, poly-3,4-ethylenedioxythiophene (PEDOT)/polystyrenesulfone acid (PSS), etc.; And their combinations. Among them, the preferred conductive material for forming the source and the drain is a lower resistance when in contact with the organic semiconductor layer.

In accordance with an embodiment of the invention, more than one material may be combined to reduce contact resistance and increase interface strength. In accordance with an embodiment of the present invention, a highly doped germanium or indium tin oxide can be used as both a substrate and a bottom-gate.

Known methods in the art can be used, such as, but not limited to, spin coating, spray coating, dip coating, blade coating, casting, roll coating, rod coating, die coating, chemical vapor deposition (CVD), sputtering, vacuum. Dry and wet processing methods such as vapor deposition, ion plating, pulsed laser vapor deposition, atmospheric piezoelectric plasma method, printing, inkjet, etc., to form the gate, source, and drain. At the same time, it can be combined with various patterning methods such as lithography, etching, etc. to form the desired shape. When using a wet process, the material may be dissolved or dispersed in a solvent as needed. Methods of forming gates, sources, and drains are well known to those of ordinary skill in the art and will not be described again. The thickness of the gate, the source, and the drain is not particularly limited, and is preferably selected to have good electrical properties. In general, the thickness of the source and the drain is preferably 20 to 100 nm, more preferably 20 to 60 nm. The source and the drain are disposed opposite to each other, and the interval between the two is not particularly limited. Generally, the aspect ratio of the interval is preferably 10:1 to 40:1, more preferably 20:1.

According to the present invention, the dielectric film in the organic thin film transistor includes a gate insulating layer for separating the gate and the organic semiconductor layer. The material for forming the organic semiconductor layer is not particularly limited, and an insulating material having a high dielectric constant and low conductivity is preferably used. Examples of the material as the gate insulating layer include, but are not limited to, inorganic insulating materials such as yttrium oxide (SiO ₂ ), tantalum nitride, aluminum oxide, aluminum nitride, titanium oxide, titanium nitride, tantalum oxide, tin oxide. , magnesium oxide, magnesium nitride, cerium oxide, zirconium oxide, zirconium nitride, cerium oxide, potassium oxide, lithium oxide, sodium oxide, cerium oxide, cerium oxide, cerium oxide, calcium oxide, calcium nitride, cerium oxide, oxidation钇, 钇, 镧, 镧, 鐠, 钕, 钐, 铕, 釓, 鋱, 镝, 鈥, 铒, 銩, 镱, 镏, cerium oxide, cerium nitride, cerium oxide, cerium oxide, chromium oxide, chromium nitride, molybdenum oxide, molybdenum nitride, tungsten oxide, tungsten nitride, manganese oxide, cerium oxide, iron oxide, nickel oxide, palladium oxide, Platinum oxide, copper oxide, copper nitride, silver oxide, gold oxide, zinc oxide, cadmium oxide, aluminum oxide, aluminum nitride, gallium oxide, gallium nitride, indium oxide, antimony oxide, tin oxide, lead oxide, vanadium oxide , vanadium nitride, yttrium oxide-yttrium-titanium, yttria-titanium-zirconium, lead oxide-zirconium - titanium, barium aluminum titanate, barium titanate, barium titanate, barium titanate, barium magnesium fluoride, barium-strontium-strontium oxide, barium oxide-strontium-strontium and antimony trioxide, etc.; polymer compounds such as poly醯imine, polyamine, polystyrene (PS), polyvinyl alcohol (PVA), polyvinyl phenol (PVP), polyester, polyacrylate, polymethyl methacrylate (PMMA), polyethylene, polyvinyl chloride (PVC), polyvinylidene fluoride, vinyl acetate (PVAc), polyphenylene sulfide, unsubstituted or halogen-substituted parylene, copolymerization of acrylonitrile-containing components And phenolic resin for lacquer, cyanoethyl polytriglucose, epoxy resin, phenol resin, etc.; and combinations thereof. Among the inorganic insulating materials, cerium oxide, cerium nitride, aluminum oxide, cerium oxide, and titanium oxide are preferable. Polymer materials can be used together with crosslinkers. The gate insulating layer may contain one or more layers of an inorganic insulating film and/or an organic insulating film.

The gate insulating layer can be formed by a method known in the art, for example, dry processing such as vacuum evaporation, chemical vapor deposition, sputtering, pulsed laser evaporation, ion plating, atmospheric piezoelectric plasma, etc. And wet treatment, such as spin coating, spray coating, blade coating, dip coating, casting, roll coating, rod coating, die coating, extrusion coating, printing, inkjet, etc. When using a wet process, the material may be dissolved or dispersed in a solvent as needed. When an inorganic insulating material is used, a dry process or a wet process may be appropriately selected depending on the characteristics of the material to be used. According to one embodiment of the invention, a lanthanide material can be used as both the substrate and the lower gate. In this case, the gate insulating layer can be formed by thermal oxidation.

The material forming the organic semiconductor layer is not particularly limited. An aromatic fused ring (such as pentaacene), a thiophene (such as polythiophene, oligothiophene, poly-(3-hexylthiophene), P3HT), Electron-donating group, electron-withdrawing group, and metal complexes (such as bismuth bronze (CuPc), bismuth bronze nickel (NiPc), 16- A compound such as fluocinolate bronze, titanyl phthalocyanine (TiOPc) or the like, a derivative thereof, and a combination thereof are used as a material to form an organic semiconductor layer in an organic thin film transistor. Organic semiconductor materials with high sensitivity, high selectivity, good stability, fast response rate and short recovery time can be selected as needed. The organic thin film transistor of the present invention can be used as a p-type organic thin film transistor or an n-type organic thin film transistor, and is preferably used as a p-type organic thin film transistor.

Anthocyanin has good heat resistance and chemical stability, and is therefore an organic semiconductor material with high applicability. For oxidizing gases (such as O ₂ , NO, NO ₂ ), because the electron affinity of phthalocyanine is smaller than that of oxidizing gas, when the oxidizing gas contacts and adsorbs the surface of the phthalocyanine film, the electrons of phthalocyanine Will transfer to the oxidizing gas, so that the oxidizing gas is negatively charged, the surface of the phthalocyanine film is positively charged; when the oxidizing gas diffuses to the bulk phase of the phthalocyanine film, it is negatively charged, and the phthalocyanine film is negatively charged. The bulk phase is positively charged. Therefore, the surface of the phthalocyanine film and the bulk phase will release carriers (holes), which will increase the conductivity of the phthalocyanine film and reduce the resistance and activation energy. In contrast, for reducing gases (eg, H ₂ , CO, C ₂ H ₅ OH, NH ₃ ), when the phthalocyanine contacts and adsorbs the reducing gas, the electrons of the reducing gas are transferred to the phthalocyanine. The film, therefore, the conductivity of the phthalocyanine film is reduced, and the electrical resistance and activation energy are increased. Therefore, phthalocyanine is suitable as an organic semiconductor material for sensing a gas. According to a specific embodiment, the organic semiconductor layer of the present invention comprises a film formed of a metal-cyanine complex. Preferably, the organic semiconductor layer of the present invention comprises a film formed of titanyl cyanine. More preferably, the organic semiconductor layer of the present invention is composed of titanyl phthalocyanine.

Methods known in the art can be used (such as, but not limited to, spin coating, spray coating, dip coating, blade coating, casting, roll coating, rod coating, die coating, chemical vapor deposition (CVD), sputtering, vacuum). A thin film of the above organic semiconductor material is formed by vapor deposition, ion plating, pulsed laser vapor deposition, atmospheric piezoelectric plasma method, dry or wet processing such as printing or inkjet to form an organic semiconductor layer. When using a wet process, the material may be dissolved or dispersed in a solvent as needed. Methods of forming thin films of organic semiconductor materials are well known to those of ordinary skill in the art. For example, phthalocyanine has high thermal stability, and therefore, a phthalocyanine film can be formed by, for example, vacuum evaporation. In this example, vapor deposition conditions (eg, evaporation rate, substrate temperature, etc.) may be selected as needed (eg, desired grain size, grain shape, crystallinity, crystalline phase, lattice gap, etc.). For example, when the titanium oxyfluoride cyanine film is vacuum-evaporated, the substrate temperature may be from 140 ° C to 250 ° C, preferably from 150 ° C to 220 ° C, more preferably from 160 ° C to 180 ° C.

After the organic semiconductor layer is formed, post-treatment (for example, heat treatment) may be performed as needed. In addition, the organic semiconductor layer may be doped as needed. Dopings which may be used include, for example, but are not limited to, ammonium ions, halogen compounds, acetylcholine; alkaline earth metals; alkali metals; rare earth metals; transition metal compounds; Lewis acid; organic acids; proton acids; Electrolyte anion, etc. Doping may be performed after the formation or formation of the organic semiconductor layer. The thickness of the organic semiconductor layer is not particularly limited and may be selected to form a uniform film. The thickness can also be adjusted depending on the required electrical properties. In general, the thickness of the organic semiconductor layer is preferably from 30 to 100 nm, more preferably from 40 to 60 nm.

According to an embodiment of the invention, the dielectric film in the organic thin film transistor comprises a Self Assembly Monolayer (SAM). It can be used, for example, selected from the group consisting of octadecyltrimethoxydecane (OTMS), octadecyltrichlorodecane (OTS), octyltrichloromethane, benzyltrichlorodecane and hexamethyldioxane. At least one compound constituting the group as a material forming a self-aligning layer. Preferred are octadecyltrimethoxydecane and octadecyltrichlorodecane.

Methods known in the art can be used (such as, but not limited to, spin coating, spray coating, dip coating, blade coating, casting, roll coating, rod coating, die coating, chemical vapor deposition (CVD), sputtering, vacuum). A dry film or a wet processing method such as vapor deposition, ion plating, pulsed laser vapor deposition, atmospheric piezoelectric slurry, printing, or inkjet is used to form a film of the above material to form a self-aligning layer. When using a wet process, the material may be dissolved or dispersed in a solvent as needed. Methods of forming films of the above materials are well known to those of ordinary skill in the art and will not be described again.

According to an embodiment of the invention, the organic thin film transistor comprises a substrate. An organic thin film transistor having a gate, a source, a drain, a dielectric film, and an organic semiconductor layer may be formed on the substrate. The substrate is not particularly limited, and materials conventional in the art can be used. Examples of the substrate include, but are not limited to, a germanium substrate (single crystal germanium, polycrystalline germanium, amorphous germanium); a glass substrate (such as a tantalum-based glass, an alkali-free glass, a quartz glass, etc.); an indium tin oxide substrate; a ceramic substrate ; etc., and combinations thereof. When a glass substrate is used, it is preferably chemically strengthened or heat strengthened. The substrate can be formed using more than one material. The substrate can be one or more layers of structure. The thickness of the substrate is not particularly limited.

When a conductive substrate (for example, a germanium substrate) is used, the substrate can also serve as a gate. In accordance with an embodiment of the invention, highly doped germanium or indium tin oxide can be used as both the substrate and the lower gate.

The invention is described in detail below with reference to the accompanying drawings in which like reference numerals It is understood that the drawings are only schematic representations of the specific embodiments, and are not to

1A to 1C, the organic thin film electro-crystal system of the present invention includes a gate; a source; a drain; a dielectric film; and an organic semiconductor layer, wherein the dielectric film includes a gate insulating layer to separate the a gate and the organic semiconductor layer. The organic semiconductor layer forms a channel region, and can perform an on/off operation by controlling a current flowing between the source and the drain by a voltage applied to the gate.

Please refer to FIG. 1A, which is a cross-sectional view of an organic thin film transistor according to an embodiment of the present invention. As shown in the figure, the organic thin film transistor 1 mainly includes a gate electrode 11, a source electrode 17, a drain electrode 19, a dielectric film 13, and an organic semiconductor layer 15. The dielectric film 13 includes a gate insulating layer 131 to partition the gate 11 and the organic semiconductor layer 15. The dielectric film 13 further includes a self-aligning layer 133, and the organic thin film transistor 1 illustrated in FIG. 1A includes the substrate 10. In this embodiment, a germanium substrate (eg, a highly doped germanium substrate) is used as both the substrate and the gate.

Fig. 1A illustrates a structure of a bottom-gate top-contact type. First, a germanium substrate is used as the substrate 10 and the gate electrode 11, and then a dielectric film 13 (the gate insulating layer 131 and the self-aligned layer 133) is formed thereon. Then, an organic semiconductor layer 15 is formed on the dielectric film 13, and then a source 17 and a drain 19 which are spaced apart are formed on the organic semiconductor layer 15.

According to an embodiment of the invention, the organic semiconductor layer may have at least one trench, and the trench is located between the source and the drain. According to an embodiment of the invention, the organic semiconductor layer may have 1 to 4 trenches, preferably 1 to 2 trenches. The width of the groove is preferably from 20 to 80 μm, more preferably from 45 to 60 μm. The depth of the trench is preferably from 40 to 80 nm, more preferably equal to the thickness of the organic semiconductor layer. Please refer to FIG. 1B, which is a top view of an organic thin film transistor according to an embodiment of the present invention. As shown, the organic semiconductor layer 15 has a trench 151. The trench 151 is located between the source 17 and the drain 19.

Next, please refer to FIG. 1C, which is a schematic cross-sectional view of an organic thin film transistor according to an embodiment of the present invention. As shown, the organic thin film transistor 1' mainly includes a gate 11, a source 17, a drain 19, a dielectric film 13, and an organic semiconductor layer 15. The dielectric film 13 includes a gate insulating layer 131 to partition the gate 11 and the organic semiconductor layer 15. The dielectric film 13 further includes a self-aligning layer 133, and the organic thin film transistor 1' illustrated in Fig. 1C includes a substrate 10. In this embodiment, a germanium substrate is used as both the substrate and the gate. The 1Cth diagram illustrates the structure of a bottom-gate bottom-contact type. First, a germanium substrate (for example, a highly doped germanium substrate) is simultaneously used as the substrate 10 and the gate 11, and then a dielectric film 13 (the gate insulating layer 131 and the self-aligned layer 133) is formed thereon. Then, a source electrode 17 and a drain electrode 19 are formed on the dielectric film 13. Next, an organic semiconductor layer 15 is formed over the source electrode 17 and the drain electrode 19 and on the portion of the dielectric film 13.

The organic thin film transistor of the present invention can be fabricated into a sensor (for example, a gas sensor, a biosensor) after the circuit is configured. The organic thin film transistor of the present invention can be combined with microelectromechanical technology to form a sensor (e.g., a gas sensor, a biosensor). The organic thin film transistor of the present invention can be used to form a portable sensor and/or a disposable sensor. According to an embodiment of the present invention, the organic thin film transistor 1 can be designed into a circuit (for example, a gas sensor, a biosensor). The sensor made of the organic thin film transistor of the present invention conforms to the trend of miniaturization.

It should be understood that the structures in the organic thin film transistor of the present invention may be selectively changed according to actual needs (for example, thickness, relative position, relative distance), as long as the effect of the creation can be achieved, not limited to the drawings or the following. The examples are exemplified.

The organic thin film transistor of the invention has the advantages of high sensitivity, high selectivity, fast response rate, low cost and high stability. The organic thin film transistor of the present invention can be used to fabricate a gas sensor or a biosensor. The organic thin film transistor of the present invention is also advantageous for fabricating a portable sensor. The organic thin film transistor of the present invention can also be used to make a disposable sensor.

The organic thin film transistor of the present invention can be used for gas sensing to detect/detect gas concentration, and therefore, the organic thin film transistor of the present invention can be used to fabricate a gas sensor. The organic thin film transistor of the invention and the gas sensor prepared thereby can be used for detecting flammable gas or toxic gas, and can be applied to home safety, industrial safety, environmental pollution prevention, process control, road safety (drinking), food Industrial and medical fields (for example, detection, monitoring of diseases such as diabetes, lung cancer, uremia, chronic hepatitis, cirrhosis, liver failure, renal failure, periodontal disease, Helicobacter pylori infection (gastric ulcer), etc.). For example, the organic thin film transistor of the present invention has advantages of high sensitivity, high selectivity, fast response rate, and the like, and is more in line with the medical field than conventional gas sensing elements (for example, detection of liver related diseases). Application requirements for monitoring/monitoring (ammonia concentration monitoring) can be used not only for disease diagnosis but also for home care. At the same time, the organic thin film transistor of the present invention meets the requirements of miniaturization and has low cost, and is favorable for being fabricated into a portable sensor and/or a disposable sensor.

Example Organic thin film transistor component manufacturing process Substrate, gate and gate insulating layer manufacturing

Using a 3 cm × 3 cm dry oxidation 矽 substrate, the erbium oxide insulating layer (gate insulating layer) has a thickness of 100 nm, and the flow is as follows:

step one:

The substrate was immersed in acetone (acetone) for 15 minutes in an ultrasonic oscillator.

Step two:

Rinse with a detergent until the water ripple does not break away from the substrate surface during rinsing.

Step three:

The substrate was immersed in deionized water (DI water) for 15 minutes in an ultrasonic oscillator to remove the organic detergent.

Step four:

The crucible substrate was blown dry using a nitrogen gun, placed in a clean glass petri dish, and heated to a temperature of about 110 ° C for 1 hour using a hot plate to remove residual moisture on the surface.

Self Assembly Monolayer (SAM)

A very thin monolayer of octadecyltrichlorodecane (OTS) self-aligning layer was vapor deposited on a 100 nm thick ceria insulation layer. By self-aligning layers, the subsequently formed TiOPc molecules can be attracted by van der Waals or hydrogen bonding forces by the floating bonds of the SAM surface layer to form an edge-up arrangement, which makes the TiOPc OTFTs have good electrical properties. .

The SAM layer deposition steps are as follows:

step one:

On the cleaned ruthenium substrate, UV-ozone was irradiated for 15 minutes to increase the surface energy of the substrate and remove organic matter to help the OTS adhere.

Step two:

The oven was heated to 120 ° C for 2 hours by vapor deposition, and naturally cooled to allow the OTS to adhere uniformly to the crucible substrate.

Organic semiconductor layer thermal coater

The organometallic complex TiOPc with good crystallization characteristics is selected as the material of the organic semiconductor layer, and the γ phase powder with the best crystallinity is selected, and the squid is heated by electric current using a thermal evaporation method, and then the mask is used (Shadow mask L) =0.1mm, W=2.0mm) image the size of the organic semiconductor layer, the cavity vacuum value during evaporation is maintained at 3 × 10 ^- 6 torr, and the plating rate is controlled at 0.1 to 0.3 Between /sec, the organic semiconductor layer has a thickness of 40 nm, and a groove image is reserved when the mask is designed (groove W=60 μm), and Embodiment 1 (0 trench), Embodiment 2 (1 trench) can be obtained. And the organic semiconductor layer of Embodiment 3 (2 trench), wherein each trench has a width W of 60 μm and a depth of 40 nm.

Electrode metal (source, drain) vapor coater (thermal coater)

Select Ni/Au on the electrode material to form 10 nm nickel first, to avoid the probe scraping the gold due to vibration and increase the adhesion of gold; then plating 50 nm gold to match the work function. First, a 2×3.3 mm nickel ingot was placed in a tungsten boat, and the tungsten boat was heated by electric current using a thermal evaporation method, and the size of the imaged electrode was masked, and the W/L ratio was 2.0/0.1 mm. Degree 3 × 10-6 torr below, and the plating rate is controlled from 1 to 1.2 Between /sec, the thickness is 10 nm. The 2 x 3.3 mm gold ingot was then covered in the same manner to a thickness of 50 nm to obtain a source and a drain with a 0.1 mm spacing.

Component test

The test was carried out using the gas sensing system shown in Fig. 2, and the results are reported in Table 1.

The gas sensing system shown in FIG. 2 includes a semiconductor parameter analyzer 20; a cavity 21 connected to the semiconductor parameter analyzer 20 for accommodating and electrically connecting the organic thin film transistor of the present invention; ammonia gas The source 22 is connected to the cavity 21 through a gas flow controller 23; a nitrogen source 24 is connected to the cavity 21; and a pump 25 is used to evacuate the gas in the cavity 21.

Semiconductor parameter analyzer

The Keithley 2636 IV analyzer current and voltage analyzer of the Keithley 4200 semiconductor characterization system is used. The measured data mainly includes three modes: ID-VG, ID-VD and ID-Time. The computer part is used to control its details. The following test Mainly measure the change of current before and after passing the gas, and judge by ID-VG measurement mode, the gate voltage is maintained at -15 V, the gate voltage is gradually reduced from 10 V to -25 V, and the gas is introduced separately. Before and after measurement.

The gas sensing (ID-VG curve) steps are as follows:

Step 1 (Atmospheric environment)

Put the organic thin film transistor test piece into the cavity and close the door for one minute to reduce the interference of light on the component. In order to eliminate the influence of moisture and temperature, the humidity will be controlled to 58 to 62% before each measurement. The temperature is controlled between 22 and 25 °C. After that, the voltage is applied and the first ID-VG curve is measured as the reference line.

Step 2 (ammonia environment)

The gas flow controller (Mks Type 246) was used to sense the ammonia gas of 500 ppb (parts per billion), and waited for five minutes to measure the second component test system of the present invention with the ID-VG curve as the sensing. The curves were tested with the organic thin film transistors of Examples 1, 2 and 3.

Calculation of gas sensing sensitivity (ammonia/atmospheric ratio, NH ₃ /Air):

The gas sensing sensitivity is expressed by the following formula 1. The ammonia/atmospheric ratio is defined as the ratio of the gate current (V _G ) to the on current change before and after the sensing at -25V.

It can be seen from the above table that the ammonia/atmosphere ratio is used to indicate the magnitude of the change before and after the sensing. The number of grooves is 0, and the ammonia/atmosphere ratio is 6.05. The groove structure is used to greatly increase the ammonia/atmospheric ratio. When the number of slots is 1, the number is increased to 16.57 (about 2.74 times), and when the number of grooves is 2, it can be increased to 29.41 (up 4.86 times).

The organic thin film transistor of the invention can be operated at normal temperature, and the organic thin film transistor of the invention has the advantages of high sensitivity, high selectivity, fast response rate, low cost and high stability. Moreover, the organic thin film transistor of the present invention can be used for gas sensing, including sensing of oxidizing gas and reducing gas.

The above examples are merely illustrative of the organic thin film transistor of the present invention and its preparation, and are not intended to limit the present invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the claims of the present invention should be as set forth in the appended claims.

1,1’. . . Organic thin film transistor

10. . . Substrate

11. . . Gate

13. . . Dielectric film

131. . . Gate insulation

133. . . Self-alignment layer

15. . . Organic semiconductor layer

151. . . Trench

17. . . Source

19. . . Bungee

20. . . Semiconductor parameter analyzer

twenty one. . . Cavity

twenty two. . . Ammonia source

twenty three. . . Gas flow controller

twenty four. . . Nitrogen source

25. . . Pump

1A is a schematic cross-sectional view of an organic thin film transistor according to an embodiment of the present invention;

1B is a top view of an organic thin film transistor according to an embodiment of the present invention;

1C is a schematic cross-sectional view of an organic thin film transistor according to an embodiment of the present invention;

2 is a schematic diagram of a gas sensing system in accordance with an embodiment of the present invention.

1. . . Organic thin film transistor

10. . . Substrate

11. . . Gate

13. . . Dielectric film

131. . . Gate insulation

133. . . Self-alignment layer

15. . . Organic semiconductor layer

17. . . Source

19. . . Bungee

Claims (9)

An organic thin film transistor comprising: a gate; a source; a drain; a dielectric film formed on the gate; and an organic semiconductor layer formed on the dielectric film, wherein the dielectric film includes a gate A pole insulating layer separates the gate and the organic semiconductor layer, and the organic semiconductor layer has at least one trench between the source and the drain, and the organic semiconductor layer has a thickness of 40 to 60 nm. The organic thin film transistor according to claim 1, wherein the organic semiconductor layer comprises a titanyl phthalocyanine film. The organic thin film transistor according to claim 1, wherein the dielectric film comprises a self-aligning layer. The organic thin film transistor according to claim 3, wherein the self-aligning layer contains an octadecyltrimethoxydecane (OTMS), octadecyltrichlorodecane (OTS), and octyl A compound of at least one group consisting of chlorodecane, benzyltrichlorodecane and hexamethyldioxane. The organic thin film transistor according to claim 4, wherein the self-aligning layer contains octadecyltrimethoxydecane and/or octadecyltrichlorodecane. An organic thin film transistor according to claim 1, wherein The organic semiconductor layer has 1 to 2 trenches. The organic thin film transistor according to claim 1, further comprising a substrate, wherein the substrate is a germanium substrate. The organic thin film transistor according to claim 1, wherein the gas system is selected from the group consisting of an oxidizing gas or a reducing gas. A gas sensor having an organic thin film transistor according to any one of claims 1 to 8.