JPH08111166A - Electron pulse emitting device and display device - Google Patents

Abstract

PURPOSE: To obtain pulsatively high electron emitting current density under low operating voltage by forming a second electrode on a first electrode through a ferroelectric substance film, and opposing a third electrode to the second electrode through a space. CONSTITUTION: A first electrode 2 is formed on a silicon board 1, and a second electrode 4 is formed on the electrode 2 through a ferroelectric substance film 3. A third electrode 5 opposed to the electrode 4 through a space is formed on the electrode 4. Here, a positive pulse is impressed on the electrode 2 between the electrode 2 and the electrode 4, and since a device is composed of the electrode 2, the ferroelectric substance film 3 and the electrode 4 and charging is performed, an electron is accumulated to the electrodes 2 and 4. When a negative pulse is impressed on the electrode 2 between the electrode 2 and the electrode 4, polarization of the ferroelectric substance film 3 is reversed, and the electron is emitted toward the electrode 5 from the electrode 4 by a DC bias 6. An electron 28 restricted by a defect level of the ferroelectric substance film 3 is accelerated by an electric field imposed on the ferroelectric substance film 3, and jumps out to a vacuum level 24 while hopping between defect levels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron pulse emission device which uses, as a cold cathode electron emission surface, one electrode surface of a capacitance device having a ferroelectric film or a dielectric film having a high dielectric constant as a capacitance insulating film. The present invention relates to a display device using the electron pulse emission device.

[0002]

2. Description of the Related Art The moving speed of electrons in a solid-state element is at most about 1/1000 of the speed of light, and the operating speed of the solid-state element is limited. Further, the characteristics of these solid-state devices have a drawback that they are easily affected by radiation and temperature changes. In recent years, in order to overcome these drawbacks of solid-state devices, attempts have been made actively to make minute vacuum tubes in solids by using fine processing technology.

Cold cathodes of various shapes are used in these micro vacuum tubes. Among them, the needle-shaped electrode is one.
Since a high emission electron density of 000 A / cm ² or more can be easily obtained, it has been widely studied. A planar cathode structure utilizing the avalanche breakdown in a semiconductor and the tunnel effect of an insulating film or a Schottky barrier has also been studied.

An example of a conventional electron pulse emission device having a flat cathode structure will be described below. FIG. 6 is a sectional view of a main part of a conventional electron pulse emission device.

As shown in FIG. 6, in the conventional electron pulse emission device, a ferroelectric film 3 is sandwiched between a first electrode 2 and a second electrode 4, and a ferroelectric film is formed on the second electrode 4. An opening 4a for exposing the surface of the substrate 3 is provided. In such a configuration, the polarization of the ferroelectric film 3 is abruptly inverted by the pulse voltage from the AC pulse power supply 7, so that the ferroelectric film 3 is
Attempts have been made to release electrons confined by the polarization charge on the surface of helium in a pulsed manner, and current densities above 1 A / cm ² have been obtained (eg H. Gundl et al. Appl. Phys. Let.
t., Vol.54, pp.2071, 1989).

[0006]

However, in the above-mentioned conventional needle-like electrode structure, current concentrates on the tip of the cathode, so that the tip evaporates and the emission current characteristic changes with time. There was a problem that the emission current characteristics became unstable due to the adsorption and desorption of gas.

On the other hand, the flat cathode structure utilizing the avalanche breakdown and the tunnel effect has a problem that the operating voltage becomes high because a high electric field is required for electron emission. Furthermore, since many of the micro vacuum tubes using these cold cathodes operate in direct current, there is a problem that the emission electron current is saturated due to the space charge limiting effect.

This space charge limiting effect can be avoided by pulsing electrons into the space if only the instantaneous current value matters. For example, electron emission from a ferroelectric surface using polarization reversal of a ferroelectric substance is an example (eg H. Gundl et al. Appl. Phys. Lett., Vol.5).
4, pp.2071, 1989 and JP-A-5-325777), the amount of electrons emitted here is at most only the amount of charge combined with the polarization charge of the ferroelectric film, so that a high emission electron current density is obtained. Can't hope In addition, since the electron emission surface is a ferroelectric surface, there is a problem that the electron emission characteristic becomes unstable due to adsorption and desorption of gas.

In order to solve this problem, the inventors have
The surface of the ferroelectric substance was covered with a metal electrode, and electrons were extracted from the metal electrode by an electric field applied between the metal electrode and a trigger plate separated by an insulating film to stabilize the electron emission characteristics. See Kaihei 6-259304). However, in this structure, although the electron emission characteristics are improved as compared with the conventional structure, the withstand voltage of the insulating film between the metal electrode and the trigger plate must be high, and the circuit for driving this device is The new challenge of complexity has arisen.

The present invention solves the above-mentioned conventional problems, has no space charge limiting effect, can obtain a high electron emission current density in a pulsed manner with a low operating voltage, and has little characteristic fluctuation or characteristic deterioration. An object is to provide an electron pulse emission device and a display device having a flat cathode structure.

[0011]

In order to achieve this object, an electron pulse emission device of the present invention comprises a support substrate, a first electrode formed on the support substrate, and a first electrode on the support substrate. A formed ferroelectric film, a second electrode formed on the ferroelectric film without contacting the first electrode, and a third electrode facing the second electrode with a space in between. It has a configuration consisting of.

Further, the display device of the present invention has a plurality of first electrodes on one main surface, a ferroelectric film formed on the first electrodes, and a first ferroelectric film on the ferroelectric film. Support electrode having a plurality of second electrodes formed without contacting the electrodes of the above, and an insulating layer having an opening at the intersection of the first electrode and the second electrode, a transparent conductive layer and a phosphor layer Has a structure in which a transparent substrate formed in order is opposed to and held by a space, and is sealed at a peripheral portion.

[0013]

With the above-described structure, the electron pulse emission device has a structure in which, in addition to the electrons accumulated as capacitive coupling in the second electrode, the electrons confined to the interface state between the second electrode and the ferroelectric film Since the electrons confined to the defect levels in the dielectric film can be used as the emitted electrons, the emission current density can be increased.

The support substrate is an n-type semiconductor substrate, and the first
Since the electrode of (1) is composed of the p-type diffusion layer, even the electrons diffused and injected from the pn junction can be used as the emitted electrons, so that the emission current density further increases.

Further, when the thickness of the ferroelectric film is set to about 200 nm, the polarization can be inverted at a low voltage of about ± 5 V, and the electrons can be emitted at a low voltage. Furthermore, since the electron emission surface has a planar structure covered with the second electrode, it is possible to realize an electron pulse emission device in which the emission current is not concentrated and the influence of gas adsorption / desorption is small. Furthermore, since the operation may be performed by applying an AC pulse voltage between the first electrode and the second electrode, the circuit configuration required for the operation is simplified.

Further, by using a transparent substrate on which a transparent conductive layer is formed as a third electrode of the above-mentioned electron pulse emission device and a phosphor layer is laminated thereon, a thin display device capable of low voltage operation is realized. it can.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electron pulse emission device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an electron pulse emission device according to the first embodiment of the present invention. In FIG. 1, 1 is a supporting substrate such as a silicon substrate or a glass substrate, 2 is a first electrode made of a platinum film, 3 is a ferroelectric film of lead zirconium titanate having a thickness of 200 nm, and 4 is a platinum film. A second electrode 5 having a thickness of 10 nm is a third electrode made of aluminum, and the second electrode 4 and the third electrode 5 have a thickness of 1 m.
They are separated by about m. Reference numeral 6 is a DC bias power supply, and 7 is an AC pulse power supply, each of which constitutes a part of a drive circuit for operating the electron pulse emission device.

The operation of the electron pulse emission device constructed as above will be described below. First of all
A positive pulse is applied to the first electrode 2 between the electrode 2 and the second electrode 4 of the first electrode 2 and the ferroelectric film 3
And the capacitor composed of the second electrode 4 is charged. At this time, electrons are accumulated in the second electrode 4. Next, when a negative pulse is applied to the first electrode between the first electrode 2 and the second electrode 4, the polarization of the ferroelectric film 3 is inverted, and the DC bias 6 causes the second electrode 4 to move. The electrons are emitted from the third electrode 5 toward the third electrode 5.

The above operation will be further described with reference to the electron energy band diagram. 2 (a) is an electron energy band diagram when a pulse voltage that is positive with respect to the first electrode is applied to the second electrode, and FIG. 2 (b) is negative with respect to the first electrode. It is an electron energy band diagram when a certain pulse voltage is applied to the 2nd electrode. In these figures, 21
Is the electron energy band of the first electrode 2, 22 is the electron energy band of the ferroelectric film 3, 23 is the electron energy band of the second electrode 4, 24 is the vacuum level, 25 is the Fermi level, 26
Is an electron capacitively coupled to the second electrode 4, 27 is an electron bound to the interface level of the interface between the second electrode 4 and the ferroelectric film 3, and 28 is a defect level of the ferroelectric film 3. It is a restrained electron. In the following description, only electrons will be described as a single charge.

As shown in FIG. 2A, when a positive pulse is applied to the first electrode 2 between the first electrode 2 and the second electrode 4, the second electrode 4 is not applied. Electron 26 capacitively coupled
However, at the interface between the second electrode 4 and the ferroelectric film 3, electrons 27 bound to the interface level are accumulated, and inside the ferroelectric film 3, electrons 28 bound to the defect level are accumulated. It Next, FIG.
As shown in (b), when a negative pulse is applied to the first electrode 2 between the first electrode 2 and the second electrode 4, the polarization of the ferroelectric film 3 is inverted and the interface Electronic 2 restrained
The vacuum level 24
Jump out to. Further, the electrons 28 bound to the defect level of the ferroelectric film 3 are accelerated by the electric field applied to the ferroelectric film 3,
It jumps to the vacuum level 24 while hopping between the defect levels.

Next, an electron pulse emission device according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a sectional view of the electron pulse emission device. In FIG. 3, 31 is an n-type silicon substrate, 32 is p
A first electrode composed of a die diffusion layer, 33 is a ferroelectric film of lead zirconium titanate having a thickness of 200 nm, 34 is a second electrode of platinum film having a thickness of 10 nm, and 35 is a third electrode of aluminum. The second electrode 34 and the third electrode 35 are electrodes, and are separated by about 1 mm. 36 is a DC bias power supply and 37 is an AC pulse power supply. The first electrode 32 forms a pn junction with the n-type silicon substrate 31. An AC pulse power supply 37 is electrically connected to the first electrode 32, and the first electrode 32 and the second electrode 3 are connected.
4 and the voltage applied between the first electrode 32 and the n-type silicon substrate 31 have opposite polarities.

The operation of the second embodiment constructed as described above will be described below.

FIG. 4A is an electron energy band diagram when the DC bias power source and the AC pulse power source are not connected, and FIG. 4B is the DC bias power source and the AC pulse power source 37 connected. FIG. 4 is an electron energy band diagram when a positive pulse voltage is applied to the first electrode 32.
(C) is an electron energy band diagram when a negative pulse voltage is applied to the first electrode 32. In these figures, 41 is the electron energy band of the pn junction, 42 is the electron energy band of the ferroelectric film, 43 is the electron energy band of the second electrode 34, 44 is the vacuum level, 45 is the Fermi level,
46 is an electron capacitively coupled to the second electrode 34, and 47 is a second
Of the n-type silicon substrate 31 from the n-type silicon substrate 31 to the first electron from the interface level between the electrode 34 and the ferroelectric film 33, 48 from the defect level in the ferroelectric film 33. The electrons are injected into the electrode 32 of.

Here, a DC bias voltage is applied to the first
When a positive pulse voltage is applied to the electrode 32 of FIG.
As shown in FIG.
6, electrons 47 bound to the interface state are stored in the interface between the second electrode 34 and the ferroelectric film 33, and electrons 48 bound to the defect level are stored in the ferroelectric film 33. In addition, since the pn junction is forward-biased, electrons 49 are diffused and injected from the n-type silicon substrate 31 into the first electrode 32, and some of them are deposited on the ferroelectric film 33 and the first electrode 32. The electrons 47 are restrained by the interface state at the interface with the electrode 32.

Next, when a negative pulse is applied to the first electrode 32, the polarization of the ferroelectric film 33 is inverted as shown in FIG. 4C, and the electrons 47 bound to the interface state are inverted. An electric field due to the polarization charge causes the electric field to jump to the vacuum level 44. Furthermore, the electrons 48 bound to the defect level of the ferroelectric film 33
It is accelerated by the electric field applied to the ferroelectric film 33 and jumps to the vacuum level 44 while hopping between the defect levels. In addition to this, the electrons 47 confined to the interface state between the first electrode 32 and the ferroelectric film 33 are also accelerated by the electric field to form the vacuum level 44.
Will be released to.

Although the n-type silicon substrate is used as the substrate, the p-type diffusion layer is used as the first electrode, and the pn junction is used in this embodiment, the n-type well is formed on the p-type silicon substrate. A similar electron-emitting device can be formed by forming the same and forming a p-type diffusion layer in the n-type well and using it as the first electrode. If the pn junction is not used, an n-type diffusion layer may be formed on the p-type silicon substrate and this n-type diffusion layer may be used as the first electrode.

Next, a display device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a three-dimensional cross-sectional view of the display device. In FIG. 5, 51 is an n-type silicon substrate, 52 is a first electrode made of a p-type diffusion layer, and 53.
Is a ferroelectric film such as PZT, 54 is a second electrode made of a platinum film formed so as to be orthogonal to the first electrode 52, 55 is an insulating layer made of a silicon oxide film, and 56.
Is an opening provided in the insulating layer 55, 57 is a phosphor layer, 58 is a third electrode made of a transparent conductive layer, 59 is a transparent substrate, 60 is a DC bias power supply, and 61 is an AC pulse power supply. Although not shown in the drawing, the first electrode 52 and the second electrode 54 are respectively provided with an AC pulse power supply 61 via a switch.
Be connected to. Thus, the present embodiment is
A large number of electron emitting portions are provided on the n-type silicon substrate 51, and a transparent substrate 59 on which a phosphor layer 57 and a transparent conductive layer 58 are formed is placed facing the n-type silicon substrate 51, and around each substrate. The display device is configured by vacuum sealing.

That is, a large number of first electrodes 52 arranged in parallel on the n-type silicon substrate 51 and the ferroelectric film 5 are formed.
A large number of second electrodes 54 arranged in parallel with each other through 3 are arranged at right angles to each other. Multiple second electrodes 54
Are electrically insulated from each other by an insulating layer 55 made of a silicon oxide film having an opening 56 for emitting electrons into a vacuum. The ends of the first electrode 52 and the second electrode 54 are connected to an AC pulse power supply 61 via switches (not shown). On the other hand, AC pulse power supply 61
On the other hand, the third electrode 58 for capturing the emitted electrons biased by the DC bias power source 60 is a transparent conductive layer formed on the transparent substrate 59 facing the electron emission surface with a space from the opening 56. For example, indium tin oxide (ITO) or the like is used. Further, in this embodiment, the phosphor 57 is applied on the surface of the transparent conductive layer 58, which is the electron arrival surface. It should be noted that the silicon substrate 51 and the transparent substrate 59 can be kept uniform in space by providing a spacer on the insulating layer 55 and superposing them on each other.

The operation of the display device configured as described above will be described below. First, the AC pulse power supply 61 charges and discharges a capacitor composed of the first electrode 52, the ferroelectric film 53, and the second electrode 54 in the same manner as in the electron pulse emission device shown in FIG. The emission location is the first electrode 52 and the second electrode 54.
The points on the grid are selected by combining the open / closed states of the switches (not shown) connected to each of them. As described above, the electrons emitted from the opening 56 of the selected arbitrary lattice point are accelerated by the electric field by the DC bias power source 60 and reach the third electrode 58. Since it is coated on the surface of the third electrode 58, the accelerated electrons collide with the phosphor 57 and cause it to emit light. That is, since it is possible to select and emit light at any place on the inner surface of the transparent substrate 59, it can be used as a flat image display device.

In the display device in the above-mentioned embodiment, an example in which the p-type diffusion layer formed on the n-type silicon substrate 51 is used as the first electrode 52 has been described, but this uses a pn junction to improve efficiency. However, if the diffusion layer is simply used as the wiring, it is not necessary to pay attention to the conductivity type. Also, instead of using a semiconductor substrate as the substrate,
A plurality of first electrodes are formed of a conductive material on an insulating substrate, a ferroelectric film is formed so as to cover the first electrodes, and the first electrodes are orthogonal to the first electrode on the ferroelectric film. Second to do
The same display device can be formed by forming the electrodes of.

Further, in the display device in the above embodiment, an example in which a platinum film is used as the second electrode 54 has been described, but a metal having a low work function other than the platinum film is used,
Alternatively, magnesium oxide (Mg
By coating a material having a high electron emission efficiency such as O) or cesium (Cs), a display device including an electron pulse emission device having a higher electron emission efficiency can be configured.

In addition, when the display device is colorized,
A phosphor film exhibiting different colors may be formed on the transparent substrate 59 corresponding to the intersection of the first electrode 52 and the second electrode 54, or the phosphor film 57 is selected to emit white light. However, a mosaic-shaped color filter may be stacked on the transparent substrate 59. At this time, the first electrode 52 and the second electrode 5
If the intersections with 4 are offset from each other by a half pitch between rows or columns, vivid color display is possible.

When a silicon single crystal substrate is used as the substrate, the electrodes can be formed by the usual semiconductor device manufacturing method, and a high-performance drive circuit can be formed around the display portion, which is small and high-performance. A display device can be configured.

When a transparent substrate on which a polycrystalline silicon film or an amorphous silicon film is formed is used as the substrate, the performance is slightly inferior to the case where a silicon single crystal substrate is used, but a large screen is obtained. A display device can be configured.

[0037]

According to the present invention, the first invention formed on the supporting substrate
Electrode and a ferroelectric film formed on the first electrode,
It is composed of a second electrode formed on the ferroelectric film without contacting the first electrode, and a third electrode opposed to the second electrode through a space, and is stored in the electrode as capacitive coupling. Electrons, electrons bound to the interface state between the electrode and the ferroelectric film,
By emitting electrons confined to the defect level in the ferroelectric film, it is possible to realize an electron pulse emission device with a low voltage and a high emission current density. For example, if the ferroelectric film has a thickness of about 200 nm, it is possible to invert the polarization of the ferroelectric substance at a low voltage of about ± 5V.
It can be operated at low voltage.

Further, an n-type silicon substrate is used as a substrate, a p-type diffusion layer is used as a first electrode, a ferroelectric film and a second electrode are sequentially formed thereon, and a third electrode is formed thereon. Since the electrons injected from the pn junction can be used as the emitted electrons by the installation, the emission current density can be further increased.

Further, since the electron emission surface has a planar structure of metal or oxide, it is possible to realize an electron pulse emission device which is free from concentration of emission current and is hardly affected by adsorption and desorption of gas.

Further, by applying the above-mentioned electron pulse emission device and applying a phosphor film on the third electrode in advance, the phosphor film is excited by the emitted electrons to emit light, An extremely thin display device can be realized.

Further, a single crystal silicon substrate is used as a substrate of the display device, and a driving circuit can be integrally formed in the peripheral portion of the display portion, so that the number of input terminals of the display device and an external circuit can be simplified. You can

[Brief description of drawings]

FIG. 1 is a sectional view of an electron pulse emission device according to a first embodiment of the present invention.

FIG. 2 (a) shows a first example of the same electron pulse emission device.
(B) is an electron energy band diagram when a pulse voltage that is positive to the second electrode is applied to the second electrode. Energy band diagram when applied to the electrodes of

FIG. 3 is a sectional view of an electron pulse emission device according to a second embodiment of the present invention.

4A is an electron energy band diagram when a DC bias voltage and a pulse voltage are not applied in the same electron pulse emission device, and FIG. 4B is a DC bias voltage applied in the same electron pulse emission device. In the electron energy band diagram (c) when a positive pulse voltage is applied to the p-type diffusion layer, a DC bias voltage is applied and a negative pulse voltage is applied to the p-type diffusion layer in the electron pulse emission device. Energy band diagram when

FIG. 5 is a three-dimensional cross-sectional view of a display device according to an embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a conventional electron pulse emission device.

[Explanation of reference numerals] 1 support substrate 2 first electrode 3 ferroelectric film 4 second electrode 5 third electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Arita 1-1 Sachimachi, Takatsuki City, Osaka Prefecture Matsushita Electronics Co., Ltd. (72) Inventor Akihiro Matsuda 1-1, Sachimachi, Takatsuki City, Osaka Matsushita Electronics Industry Within the corporation

Claims (7)

[Claims] 1. A support substrate, a first electrode formed on the support substrate, a ferroelectric film formed on the first electrode, and the ferroelectric film formed on the ferroelectric film. An electron pulse emission device comprising a second electrode formed without contact with the first electrode, and a third electrode facing the second electrode with a space in between. 2. The electron pulse emission device according to claim 1, wherein the supporting substrate is a semiconductor substrate of one conductivity type, and the first electrode is a diffusion layer of the other conductivity type formed on the semiconductor substrate. 3. A plurality of first electrodes on one main surface, a ferroelectric film formed on the first electrode, and a contact with the first electrode on the ferroelectric film. A plurality of second electrodes which are formed without any action, a support substrate including an insulating layer having an opening at an intersection of the first electrode and the second electrode, a transparent conductive layer and a phosphor layer are sequentially formed. A display device in which the transparent substrate is held so as to face it through a space and is sealed in the peripheral portion. 4. The display device according to claim 3, wherein the support substrate is a semiconductor substrate of one conductivity type, and the first electrode is a diffusion layer of the other conductivity type formed on the semiconductor substrate. 5. The display device according to claim 4, wherein a drive circuit for supplying electric signals to the plurality of first electrodes and the plurality of second electrodes is provided on the supporting substrate. 6. The display device according to claim 3, 4 or 5, wherein the intersections of the plurality of first electrodes and the plurality of second electrodes are offset by a half pitch between rows or columns. 7. The phosphor of two or more types is independently applied in a matrix form on a transparent substrate corresponding to the intersections of the plurality of first electrodes and the plurality of second electrodes. 4,
5. The display device according to 5 or 6.