WO2017030267A1

WO2017030267A1 - Planar liquid crystal-gate-field effect transistor comprising dipole control layer and super-sensitivity tactile sensor using same

Info

Publication number: WO2017030267A1
Application number: PCT/KR2016/003923
Authority: WO
Inventors: 김영규; 김화정; 서주역
Original assignee: 경북대학교산학협력단
Priority date: 2015-08-19
Filing date: 2016-04-15
Publication date: 2017-02-23
Also published as: KR20170023232A; KR101828330B1

Abstract

The present invention relates to a liquid crystal-gate-field effect transistor comprising a dipole control layer and a tactile sensor using the same, and comprises: a substrate; a gate electrode formed on the substrate; a source electrode formed on the substrate to be spaced from the gate electrode; a drain electrode formed on the substrate to be spaced from the source electrode; a channel layer formed on the substrate so as to cover the source electrode and the drain electrode, the channel layer electrically connecting the source electrode and the drain electrode; a liquid crystal layer formed on the substrate so as to connect the gate electrode and the channel layer; and a dipole control layer interposed between the liquid crystal layer and the channel layer so as to minimize induction of generation of electric charges in the channel layer by the liquid crystal layer. The present invention, as described above, combines a conventional liquid crystal-gate-field effect transistor structure with a polymer material having a low permittivity such that leakage of drain current through the channel layer, in zero gate voltage state, is substantially reduced, thereby both providing the function of a transistor and providing the function of a tactile sensor having a substantially improved sensing sensitivity.

Description

Planar Liquid Crystal-Gate-Field Effect Transistor with Dipole Control Layer and Supersensitive Tactile Sensor Using the Same

The present invention relates to a planar liquid crystal-gate-field effect transistor including a dipole control layer and a supersensitive tactile sensor using the same. More particularly, a polymer having a low dielectric constant is incorporated into a structure of a conventional liquid crystal-gate-field effect transistor. By significantly reducing the leakage of drain current through the channel layer at a gate voltage of zero, thereby providing a transistor and a dipole control layer that can simultaneously provide the function of a tactile sensor with significantly improved sensing sensitivity. It relates to a gate-field effect transistor and a supersensitive tactile sensor using the same.

In general, as shown in FIG. 1, the planar liquid crystal-gate-field effect transistor 1 ′ includes a substrate 10 ′, a gate electrode 20 ′ formed on the substrate 10 ′ at a predetermined interval, A source layer 30 'and a channel layer 50' electrically connecting the source electrode 30 'and the drain electrode 40' on the substrate 10 'and the channel layer ( 50 ') and the gate electrode 20' are formed to have a structure including a liquid crystal layer 60 'which functions as a gate insulating layer and a sensing function.

The conventional planar liquid crystal-gate-field effect transistor 1 'as described above has a drain current value through the channel layer 50' in a state where a voltage is applied to the gate electrode, and a voltage is applied to the gate electrode 20 '. In the state in which the physical stimulus is applied to the liquid crystal layer 60 'from the outside and the charge density of the channel layer 50' is increased due to the orientation change of the liquid crystal molecules M 'of the liquid crystal layer 60'. It has a function as a sensor for detecting a physical stimulus applied to the liquid crystal layer 60 'from the outside by using a change amount of the drain current value through the channel layer 50'.

However, the above-described conventional planar liquid crystal-gate-field effect transistor 1 'has a gate electrode (as shown in FIG. 2) due to the structure in which the liquid crystal layer 60' is in direct contact with the channel layer 50 '. The liquid crystal molecules M 'of the liquid crystal layer 60' induce a charge generation in the channel layer 50 'even when no voltage is applied to the channel layer 50', thereby generating charges in the channel layer 50 '. Leakage of drain current occurs through layer 50 '.

As a result, when the base drain current value in a state where no voltage is applied to the gate electrode 20 'is not stabilized, an external physical stimulus applied to the liquid crystal layer 60' is sensed using a change amount of the drain current value. In this case, there is a problem in that the sensitivity for sensing this is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to incorporate a low dielectric constant polymer material into the structure of an existing liquid crystal-gate-field effect transistor to provide a channel layer at a '0' gate voltage. Disclosed is a liquid crystal-gate-field effect transistor including a dipole control layer which significantly reduces leakage of drain current through the same, and a tactile sensor using the same.

According to an aspect of the present invention for achieving the above object, a gate electrode formed on the substrate and the substrate and a source electrode formed to be spaced apart from the gate electrode on the substrate and spaced apart from the source electrode on the substrate A drain layer formed on the drain electrode and the substrate to cover the source electrode and the drain electrode, and a channel layer electrically connecting the source electrode and the drain electrode, and connecting the gate electrode and the channel layer on the substrate. And a dipole control layer interposed between the liquid crystal layer and the channel layer to minimize charge generation in the channel layer by the liquid crystal layer. A gate-field effect transistor is provided.

The dipole control layer may be a polymer material having a lower dielectric constant than the channel layer.

In addition, the dipole control layer is characterized in that it comprises poly methyl methacrylate (PMMA).

The channel layer may be any one of an organic semiconductor layer, an inorganic semiconductor layer, and an organic-inorganic mixed semiconductor layer.

In addition, the liquid crystal layer may include liquid crystal molecules whose molecular orientation changes according to the voltage of the gate electrode.

In addition, the liquid crystal layer is characterized in that it comprises nematic liquid crystal molecules.

The liquid crystal layer is characterized in that it has a function as a gate insulating layer for insulating between the channel layer and the gate electrode.

In addition, a protective wall formed on the channel layer and the gate electrode to surround at least a portion of the channel layer and the gate electrode, characterized in that the liquid crystal layer is formed inside the protective wall.

In addition, the protective wall is characterized in that it comprises a silicon film.

The apparatus may further include a protective layer covering the upper side opening of the protective wall.

In addition, the protective layer is characterized in that it comprises a stretched polypropylene film.

According to another aspect of the present invention for achieving the above object, there is provided a tactile sensor using a liquid crystal-gate-field effect transistor comprising a dipole control layer of the substrate.

According to the present invention as described above, by incorporating a low dielectric constant polymer material into the structure of the conventional liquid crystal-gate-field effect transistor to significantly reduce the leakage of the drain current through the channel layer in the '0' gate voltage state, the transistor It is possible to simultaneously provide the function of the tactile sensor with significantly improved sensing and sensing sensitivity.

1 schematically shows a conventional planar liquid crystal-gate-field effect transistor.

2 illustrates a state in which charge generation of a channel layer is induced by liquid crystal molecules of a liquid crystal layer of a conventional planar liquid crystal-gate-field effect transistor.

3 is a schematic diagram of a planar liquid crystal-gate-field effect transistor including a dipole control layer in accordance with an embodiment of the present invention.

4A, 4B and 4C are schematic diagrams for explaining the operation of a planar liquid crystal-gate-field effect transistor including a dipole control layer according to an embodiment of the present invention.

FIG. 5 is a graph illustrating a change in drain current according to drain voltage according to the drain voltage of a planar liquid crystal-gate-field effect transistor including a dipole control layer according to an embodiment of the present invention for each gate voltage.

FIG. 6 is a graph showing changes in drain currents when a flow of nitrogen gas having different intensities is applied to a planar liquid crystal-gate-field effect transistor including a dipole control layer according to an embodiment of the present invention. to be.

Hereinafter, with reference to the drawings will be described the present invention in more detail. It should be noted that like elements in the figures are denoted by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

Referring to FIG. 3, a planar liquid crystal-gate-field effect transistor 1 including a dipole control layer according to an embodiment of the present invention includes a substrate 10, a gate electrode 20, a source electrode 30, and a drain electrode. 40, a channel layer 50, a liquid crystal layer 60, a dipole control layer 70, a protective wall 80, and a protective layer 90.

The substrate 10 may be a silicon substrate, a glass substrate, or a plastic substrate.

The gate electrode 20 is formed on the substrate 10, and for example, a conductive material such as gold (Au), silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), a polymer, or sulfide It may be formed of a transparent electrode such as tungsten.

The source electrode 30 is formed on the substrate 10 so as to be spaced apart from the gate electrode 20, and for example, gold (Au), silver (Ag), copper (Cu), nickel (Ni), and aluminum (Al). , A conductive material such as a polymer, or a transparent electrode such as tungsten sulfide.

The drain electrode 40 is formed on the substrate 10 on the opposite side of the gate electrode 20 spaced apart from the source electrode 30, for example, gold (Au), silver (Ag), copper (Cu), and nickel. It may be formed of a conductive material such as (Ni), aluminum (Al), a polymer, or a transparent electrode such as tungsten sulfide.

The channel layer 50 is formed to cover the source electrode 30 and the drain electrode 40 on the substrate 10, and serves to electrically connect the source electrode 30 and the drain electrode 40.

The channel layer 50 may be any one of an organic semiconductor layer, an inorganic semiconductor layer, or an organic-inorganic mixed semiconductor layer. If the channel layer 50 is formed of an organic semiconductor layer that is well bent and flexible, it may be implemented as a flexible transistor.

The organic semiconductor layer may be, for example, poly-3-hexylthiophene (P3HT), pentacene, tetracene, tetratracene, anthracene, naphthalene, rubrene (rubrene), coronene (coronene), perylene (perylene), phthalocyanine (phthalocyanine) or derivatives thereof, and may be formed of one or more materials of conjugated polymer derivatives including thiophene.

The liquid crystal layer 60 is formed on the substrate 10 to connect the gate electrode 20 and the channel layer 50, and functions as a gate insulating layer that insulates the gate electrode 20 from the channel layer 50. It also functions as a sensing function for sensing external physical stimuli.

The liquid crystal layer 60 includes liquid crystal molecules in the form of dipoles whose molecular orientation changes according to the voltage of the gate electrode 20, and the liquid crystal molecules are nematic liquid crystal molecules having a constant directionality. It may be formed as 4-cyano-4'pentylbiphenyl (4-cyano-4'pentylbiphenyl).

The dipole control layer 70 is a polymer material having a lower dielectric constant than the channel layer 50 and is interposed between the channel layer 50 and the liquid crystal layer 60 to prevent the channel layer from directly contacting the liquid crystal layer. In a state in which the voltage is not stable (hereinafter, referred to as a '0' gate voltage state), the charge is induced in the channel layer 50 by the liquid crystal molecules of the liquid crystal layer 60 to minimize the generation of the charge in the channel layer 50. It acts as a poly methyl methacrylate (Poly methyl methacrylate, PMMA) can be formed.

The dipole control layer 70 as described above minimizes the generation of electric charge in the channel layer 50 by the liquid crystal molecules of the liquid crystal layer 60 in the '0' gate voltage state, and through the drain electrode in the '0' gate voltage state. By minimizing the occurrence of leakage current, it serves to stabilize the base drain current value of the '0' gate voltage state.

As a result, a voltage is applied to the gate electrode 20 to electrically polarize the dipole control layer 70, thereby stabilizing the drain current value in the state where charge is generated in the channel layer 50. As a physical stimulus is applied to the liquid crystal layer 60 to change the orientation of the liquid crystal molecules of the liquid crystal layer 60, the liquid crystal layer from the outside through an increase in the drain current value generated due to an increase in the charge density generated in the channel layer 50. Sensing sensitivity for sensing the physical stimulus applied to 60 is greatly improved.

As described above, according to the present invention, the sensing sensitivity for sensing the physical stimulus applied to the liquid crystal layer 60 from the outside through the dipole control layer 70 is greatly improved, so that even a small vertical gas flow having a very low intensity can be sensed. It can be used as a super sensitive tactile sensor.

The passivation wall 80 is formed on the channel layer 50 and the gate electrode 20 to surround at least a portion of the channel layer 50 and the gate electrode 20 to accommodate the liquid crystal layer 60 therein. 60 is prevented from leaking to the outside, serves to adjust the thickness of the liquid crystal layer 60, a known silicon film may be used.

The protective layer 90 is installed to cover the upper side opening of the protective wall 80 to prevent the liquid crystal layer 60 from leaking to the outside and to provide a flat touch area for allowing the user to touch the liquid crystal layer 60. And oriented polypropylene film (OPP) can be used.

As shown in FIG. 4A, the planar liquid crystal-gate-field effect transistor 1 including the dipole control layer according to an exemplary embodiment of the present invention has liquid crystal molecules M of the liquid crystal layer 60 in the '0' gate voltage state. ) Have a structure that is randomly oriented.

The liquid crystal molecules M of the liquid crystal layer 60 are guided to the channel layer 50 through the dipole control layer 70 which prevents the channel layer 50 from directly contacting the liquid crystal layer 60. The charge is minimized to minimize charge generation in the channel layer 50, thereby stabilizing the base drain current value at the '0' gate voltage state.

As shown in FIG. 4B, when a voltage is applied to the gate electrode 20, the liquid crystal molecules of the liquid crystal layer 60 are aligned in a structure in which the liquid crystal molecules of the liquid crystal layer 60 are constantly oriented in the direction of the source electrode 30 and the drain electrode 40. As the dipole control layer 70 is electrically polarized by the voltage applied to the gate electrode 20, charge is induced in the channel layer 50 to generate charge in the channel layer.

As described above, the base drain current value in the '0' gate voltage state is stabilized, so that the drain current value in the state where the voltage is applied to the gate electrode 20 is also stabilized.

As shown in FIG. 4C, when a physical stimulus is applied to the liquid crystal layer 60 from the outside in the state of FIG. 4B, the bipolar control layer is changed as the alignment structure of the liquid crystal molecules M of the liquid crystal layer 60 is changed. 70 is more electrically polarized.

In addition, as the channel layer 50 is more electrically polarized, more charge is induced in the channel layer 50, thereby increasing the charge density in the channel layer 50, thereby increasing the drain current value. .

At this time, the present invention senses the physical stimulus applied to the liquid crystal layer from the outside by using an increase in the drain current value according to the increase in the charge density induced in the channel layer 50.

As described above, according to the present invention, as the base drain current value in the '0' gate voltage state is stabilized, the drain current value in the voltage applied state is stabilized, and thus, due to the physical stimulus acting on the liquid crystal layer from the outside. Sensing sensitivity is greatly improved by accurately measuring the increase in the generated drain current value, and thus it can be used as an ultra-sensitive tactile sensor that can sense even a small vertical gas flow having a very low intensity.

In the planar liquid crystal-gate-field effect transistor including the dipole control layer according to an exemplary embodiment of the present invention, as shown in FIG. 5, the drain current I _D increases rapidly as the drain voltage V _D increases. As the gate voltage V _G increases, the drain current I _D increases.

FIG. 6 is a graph illustrating a change in drain current when a flow of nitrogen gas having different intensities is applied to a planar liquid crystal-gate-field effect transistor including a dipole control layer according to an embodiment of the present invention.

In this embodiment, the experiment was performed for each nitrogen gas having an intensity corresponding to 0.5sccm, 1.0sccm, 2.0sccm, 4.0sccm, where unit sccm is the unit of flow rate Standard Cubic centimeter per minutes (cm ³ / min ).

As shown in FIG. 6, the planar liquid crystal-gate-field effect transistor 1 including the dipole control layer according to an embodiment of the present invention has a 20s band in which vertical flow of nitrogen gas having different intensities acts on the liquid crystal layer. It can be seen that the peak value of the drain current value I _D occurs at.

Accordingly, the present invention can be seen that the sensing sensitivity is high irrespective of the strength of the gas acting on the liquid crystal layer, and due to this high sensing sensitivity can be used as an ultra-sensitive tactile sensor that can sense even a small vertical gas flow with a very low intensity It can be seen that.

Although the present invention has been described in connection with the above preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

Claims

A substrate;

A gate electrode formed on the substrate;

A source electrode formed spaced apart from the gate electrode on the substrate;

A drain electrode formed on the substrate to be spaced apart from the source electrode;

A channel layer formed on the substrate to cover the source electrode and the drain electrode, the channel layer electrically connecting the source electrode and the drain electrode;

A liquid crystal layer formed to connect the gate electrode and the channel layer on the substrate;

A planar liquid crystal-gate-field effect transistor comprising a dipole control layer interposed between the liquid crystal layer and the channel layer to minimize the generation of charge generation in the channel layer by the liquid crystal layer. .
The method of claim 1,

And the dipole control layer is a polymer material having a lower dielectric constant than the channel layer.
The method of claim 2,

And the dipole control layer comprises poly methyl methacrylate (PMMA).
The method of claim 1,

And the channel layer is any one of an organic semiconductor layer, an inorganic semiconductor layer, and an organic-inorganic mixed semiconductor layer.
The method of claim 1,

And the liquid crystal layer includes liquid crystal molecules whose molecular orientation changes according to the voltage of the gate electrode.
The method of claim 1,

And a liquid crystal layer comprising nematic liquid crystal molecules. 2. The planar liquid crystal-gate-field effect transistor comprising a dipole control layer.
The method of claim 1,

And the liquid crystal layer includes a dipole control layer having a function as a gate insulating layer for insulating between the channel layer and the gate electrode.
The method of claim 1,

A protective wall formed on the channel layer and the gate electrode to surround at least a portion of the channel layer and the gate electrode,

And the liquid crystal layer is formed inside the protective wall.
The method of claim 8,

And the protective wall comprises a silicon film. 20. A planar liquid crystal-gate-field effect transistor comprising a dipole control layer.
The method of claim 8,

And a protective layer covering an upper side opening of the protective wall.
The method of claim 10,

And the protective layer comprises a stretched polypropylene film. 20. A planar liquid crystal-gate-field effect transistor comprising a dipole control layer.
A tactile sensor using a planar liquid crystal-gate-field effect transistor comprising the dipole control layer of claim 1.