CN104143573A - Optical switch element and display panel - Google Patents

Abstract

The present invention discloses an optical switch element and a display panel. The optical switch element includes a gate, a channel layer, at least one dielectric layer, a first electrode and a second electrode. The gate is disposed on a substrate. The channel layer is disposed on the substrate, and the channel layer is an oxide semiconductor. The dielectric layer is disposed between the gate and the channel layer. The first electrode is disposed on the channel layer and contacts the channel layer. The second electrode is disposed on the channel layer and contacts the channel layer to have a contact area, and there is a gap between the second electrode and the first electrode. There is an offset distance between the contact area and the gate.

Description

Optical switch element and display panel

technical field

The invention relates to an optical switch element and a display panel with the optical switch element.

Background technique

Flat panel display devices, such as liquid crystal display devices or organic light-emitting display devices, have been used in various electronic devices due to their advantages of low power consumption, low heat generation, light weight and non-radiation. Products, and gradually replace the traditional cathode ray tube (cathode ray tube, CRT) display device.

Among them, thin film transistors (thin film transistor, TFT) have been widely used in various high-end display devices. Due to the increase in the size and resolution of display devices, the demand for display color saturation has increased rapidly, and at the same time, the demand for thin film transistors has also increased. Sexual performance and stability requirements. Metal oxide semiconductors (Metal oxide semiconductors, MOSs) thin film transistors have good current output characteristics, low leakage current and electron mobility more than ten times higher than that of amorphous silicon (a-Si) thin film transistors, so The power consumption of the display device can be reduced and the operating frequency of the display device can be increased. It has the opportunity to replace the traditional amorphous silicon thin film transistor and become the mainstream driving element in the display of the next era.

In addition, an existing light sensor is composed of a photodiode and a transistor. Therefore, if the light sensor (or light sensing element) is fabricated in the thin film transistor process of the display panel, other materials will be introduced. And increasing the cost of the process will also increase the complexity and instability of the display panel process.

Therefore, how to propose an optical switch element and display panel that can detect whether it is irradiated by light or not, and how to integrate the optical switch element into the process of the display panel, thereby increasing the added value of the display panel, has become one of the important issues.

Contents of the invention

The purpose of the present invention is to provide an optical switch element and a display panel that can detect whether it is irradiated by light. In another object of the present invention, the optical switch element can also be integrated into the process of the display panel, thereby increasing the added value of the display panel.

To achieve the above purpose, an optical switch element according to the present invention includes a gate, a channel layer, at least one dielectric layer, a first electrode and a second electrode. The gate is disposed on the substrate. The channel layer is disposed on the substrate, and the channel layer is an oxide semiconductor. The dielectric layer is disposed between the gate and the channel layer. The first electrode is disposed on the channel layer and is in contact with the channel layer. The second electrode is arranged on the channel layer and contacts with the channel layer to have a contact area, and there is a space between the second electrode and the first electrode. There is an offset distance between the contact area and the gate in the projection direction of the optical switch element.

To achieve the above object, a display panel according to the present invention includes at least one optical switch element, and the optical switch element has a gate, a channel layer, at least one dielectric layer, a first electrode and a second electrode. The gate is disposed on the substrate. The channel layer is disposed on the substrate, and the channel layer is an oxide semiconductor. The dielectric layer is disposed between the gate and the channel layer. The first electrode is disposed on the channel layer and is in contact with the channel layer. The second electrode is arranged on the channel layer and contacts with the channel layer to have a contact area, and there is a space between the second electrode and the first electrode. There is an offset distance between the contact area and the gate in the projection direction of the optical switch element.

In one embodiment, the oxide semiconductor includes a metal oxide, and the metal oxide includes at least one of indium, zinc, gallium, tin and hafnium.

In one embodiment, a center plane of the grid extends through the channel layer, and the structure of the channel layer on both sides of the center plane is asymmetric.

In one embodiment, the offset distance is between 2 microns and 20 microns.

In one embodiment, the optical switch element can sense a light, and the wavelength of the light is between 0.01 nm and 500 nm.

As mentioned above, because the display panel of the present invention includes at least one optical switch element, the grid of the optical switch element is arranged on the substrate, the channel layer is arranged on the substrate, the channel layer is an oxide semiconductor, and the dielectric layer It is arranged between the gate and the channel layer. In addition, the first electrode is disposed on the channel layer and is in contact with the channel layer, and the second electrode is disposed on the channel layer and is in contact with the channel layer to have a contact area. In addition, there is an offset distance between the contact area and the gate in the projection direction of the optical switch element. In this way, the present invention can make the optical switching element and the driving element of the display panel be manufactured using the same thin film transistor process, so the optical switching element can be integrated into the process of the display panel, so not only will no other materials be introduced to increase the cost of the process , can also increase the added value of the display panel.

Description of drawings

The drawings described here are used to provide further understanding of the present invention, constitute a part of the application, and do not limit the present invention. In the attached picture:

FIG. 1A is a schematic cross-sectional view of an optical switch element according to a preferred embodiment of the present invention.

FIG. 1B is a schematic diagram of the relative positions of the gate, the channel layer, the first electrode and the second electrode of the optical switch element in FIG. 1A .

FIG. 2A and FIG. 3A are schematic cross-sectional views of optical switch elements in different forms according to a preferred embodiment of the present invention.

2B is a schematic diagram of the relative positions of the gate, the channel layer, the first electrode and the second electrode of the optical switch element in FIG. 2A and FIG. 3B is shown in FIG. 3A .

4A and 4B are characteristic curves of gate voltage and drain current under different offset distances in the optical switch element of the present invention, respectively.

FIG. 5A is a schematic diagram of the change of the drain current and time of the optical switch element of the present invention under a biased state, when it is irradiated with ultraviolet light and not irradiated with ultraviolet light.

FIG. 5B is a schematic diagram of the change of the drain current and time of the optical switch element of the present invention under the biased state, when it is irradiated with blue light and when it is not irradiated with blue light.

Explanation of reference numbers:

1, 1a, 1b: Optical switching elements

11: Substrate

12: grid

13: Channel layer

14: First electrode

15: Second electrode

16, 161, 162: dielectric layer

17: Etch stop layer

C1, C2: contact area

D1: distance

D2: offset distance

H1～H4: through hole

L: center plane

Detailed ways

The optical switch element and the display panel with the optical switch element according to the preferred embodiments of the present invention will be described below with reference to related drawings, wherein the same elements will be described with the same reference symbols. In addition, the illustrations of all the implementation aspects of the present invention are only schematic, and do not represent actual dimensions and proportions.

Please refer to FIG. 1A and FIG. 1B, wherein FIG. 1A is a schematic cross-sectional view of an optical switch element 1 according to a preferred embodiment of the present invention, and FIG. 1B is a grid 12, A schematic diagram of the relative positions of the channel layer 13 , the first electrode 14 and the second electrode 15 . Wherein, the optical switch element 1 has a thin-film transistor structure with a bottom gate (bottom gate), and can be manufactured using a thin-film transistor process.

The optical switch device 1 includes a substrate 11 , a gate 12 , a channel layer 13 , a first electrode 14 and a second electrode 15 . In addition, the optical switch element 1 further includes a dielectric layer 16 .

In practice, the substrate 11 can be a light-transmitting material, such as glass, quartz or the like, plastic, rubber, glass fiber or other polymer materials, preferably a borate alkali-free glass substrate ( aluminum silicate glass substrate). In addition, the substrate 11 can also be made of an opaque material, such as a metal-glass fiber composite board or a metal-ceramic composite board. In addition, the substrate 11 can also be a flexible substrate, depending on design requirements.

The gate 12 is disposed on the substrate 11 , and the material of the gate 12 is, for example, a single-layer or multi-layer structure composed of metals (such as aluminum, copper, silver, molybdenum, titanium) or alloys thereof. Part of the wires used to transmit the driving signal can be electrically connected to each other by using a structure of the same layer and the same process as the gate 12 , such as a scan line. In addition, in this embodiment, the dielectric layer 16 is disposed on the gate 12 and between the gate 12 and the channel layer 13, and the dielectric layer 16 can be an organic material such as an organic silicon oxide compound, or an inorganic material such as Silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, aluminum oxide, hafnium oxide, or a multilayer structure of the above materials. Here, the dielectric layer 16 completely covers the gate 12 , and optionally partially or completely covers the substrate 11 .

The channel layer 13 is disposed on the substrate 11 , and a dielectric layer 16 is interposed between the channel layer 13 and the gate 12 . Here, the position of the channel layer 13 relative to the gate 12 is disposed on the dielectric layer 16 . In practice, the channel layer 13 includes an oxide semiconductor. Wherein, the aforementioned oxide semiconductor includes metal oxide, and the metal oxide includes at least one of indium, zinc, gallium, tin, and hafnium, or other materials. Among them, the oxide semiconductor is, for example but not limited to, indium gallium zinc oxide, indium hafnium zinc oxide, zinc oxide or indium oxide, as long as the energy gap (Energy Gap) is between 3 and 4 electron volts (eV). , the present invention is not particularly limited. Because metal oxide semiconductors are quite sensitive to light, when light irradiates the metal oxide semiconductor in the channel layer, the electron-hole (hole) pairs in the channel layer will increase. By reading the signal intensity before and after light irradiation The difference can tell whether the component is photosensitive or not. Therefore, the optical switch element 1 utilizes this characteristic as a light sensing element.

The first electrode 14 and the second electrode 15 are respectively disposed on the channel layer 13 , and the first electrode 14 and the second electrode 15 are in contact with the channel layer 13 respectively. Wherein, when the channel layer 13 of the thin film transistor is not conducted, it means that the channel layer 13 is not conducted when the thin film transistor is not biased, and both the first electrode 14 and the second electrode 15 are electrically conductive. separate. Wherein, if the first electrode 14 is a source, then the second electrode 15 is a drain; otherwise, if the first electrode 14 is a drain, then the second electrode 15 is a source. Here, it is an example that the first electrode 14 is used as the drain and the second electrode 15 is used as the source. In addition, the material of the first electrode 14 and the second electrode 15 can be a single-layer or multi-layer structure composed of metals (such as aluminum, copper, silver, molybdenum, titanium) or their alloys. In addition, there is a gap between the first electrode 14 and the second electrode 15 . Wherein, part of the wires used to transmit the driving signal can use the structure of the same layer and the same process as the first electrode 14 and the second electrode 15 , such as a data line (data line). In addition, in this embodiment, as shown in FIG. 1A and FIG. 1B , the first electrode 14 and the channel layer 13 have a contact area C1 , and the second electrode 15 and the channel layer 13 have a contact area C2 .

It should be mentioned again that in this embodiment, the first electrode 14 and the second electrode 15 are directly disposed on the channel layer 13 and are in contact with the channel layer 13 as an example. However, as shown in FIG. 2A and FIG. 2B , in other In the process mode, the optical switch element 1a may further include an etch stop layer 17, the etch stop layer 17 is disposed on the channel layer 13, and one end of the first electrode 14 and the second electrode 15 are respectively self-etched A through hole H1 , H2 of the termination layer 17 is in contact with the channel layer 13 . In other words, the first electrode 14 is in contact with the channel layer 13 through the through hole H1, and the second electrode 15 is in contact with the channel layer 13 through the through hole H2, and the first electrode 14 is in contact with the channel layer 13 through the through hole H1. region C1, and the contact region C2 is where the second electrode 15 contacts the channel layer 13 through the through hole H2. Wherein, the etch stop layer 17 can be a single-layer inorganic material such as silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, aluminum oxide, hafnium oxide, or a multi-layer structure of the above materials. The etch stop layer 17 can also be an organic insulating layer material, such as organic silicon oxide.

In addition, the optical switch element 1 may further include a protective layer (shown at the end of the figure), and the protective layer is disposed on the first electrode 14 and the second electrode 15 . Here, the protective layer can protect the optical switch element 1 (or 1a) from being affected by external moisture or foreign matter.

Please refer to FIG. 1A and FIG. 1B again, in the projection direction of the optical switch element 1 (also can be regarded as the top view direction), that is, when the optical switch element 1 is projected on the substrate 11, the contact area C2 and the grid 12 There is an offset distance D2 without overlapping. In other words, in the projection direction of the optical switch element 1 , the contact region C2 is separated from the gate 12 without overlapping, and there is an offset distance D2 between them. Wherein, the offset distance D2 may be between 2 microns (μm) and 20 microns, preferably 6-10 microns. In addition, in the projection direction of the optical switch element 1 , the first electrode 14 overlaps with the gate 12 , and there is a distance D1 between the edge of the contact region C1 and the edge of the gate 12 .

In addition, the grid 12 has a central plane L, and the grids 12 on both sides of the central plane L have a symmetrical structure. In addition, the extension of the central plane L can pass through the channel layer 13 , and the structure of the channel layer 13 on both sides of the central plane L is asymmetric. In other words, the channel layer 13 has an asymmetric structure with respect to the central plane L of the gate 12 , that is, the lengths of the channel layers 13 on both sides of the central plane L are different. Here, as shown in FIG. 1B , the channel layer 13 on the right side of the central plane L is larger than the channel layer 13 on the left side. In addition to the asymmetric structure of the channel layer 13 with respect to the central plane L of the gate 12, the first electrode 14, the second electrode 15 and the etch stop layer 17 are also asymmetrical with respect to the central plane L of the gate 12. are asymmetric structures, respectively.

Next, please refer to FIG. 3A and FIG. 3B , wherein FIG. 3A is a schematic cross-sectional view of an optical switch element 1b in a different form according to an embodiment of the present invention, and FIG. 3B is a schematic view of the optical switch element 1b in the projection direction in FIG. 3A A schematic diagram of the relative positions of the gate 12 , the channel layer 13 , the first electrode 14 and the second electrode 15 .

Compared with the optical switch element 1, the optical switch element 1b differs in that: the optical switch element 1b has a thin film transistor structure with an upper gate (top gate), therefore, the gate 12 is located on the channel layer 13, and the gate 12 is connected to the channel layer 13. There are two dielectric layers 161 and 162 in sequence between the channel layer 13 . In addition, the dielectric layer 161 has two through holes H3, H4, and the first electrode 14 is in contact with the channel layer 13 through the through hole H3 to have a contact area C1, while the second electrode 15 is in contact with the channel layer 13 through the through hole H4. There is a contact area C2. Similarly, the optical switch element 1b has an offset distance D2 that does not overlap with the gate 12 in the projection direction of the substrate 11 .

Hereinafter, the light sensing principle and characteristics of the optical switch element 1a will be described with the optical switch element 1a and the corresponding diagrams in FIG. 2A and FIG. 2B (optical switch elements 1 and 1b have the same principle and characteristics).

Please refer to FIG. 4A and FIG. 4B , which respectively show the gate voltage (V) and the drain (that is, the first electrode 14 ) current under different offset distances D2 in the optical switch element 1a of the present invention. (A) Characteristic graph. In Fig. 4A, the distance 6/3 (dark) indicates that the offset distance D2 in Fig. 2B is 6 microns, and the distance D1 is 3 microns, and when the optical switching element 1a is not illuminated, the gate voltage and drain current characteristic curve. In addition, the distance 6/3 (bright) indicates that the offset distance D2 in Figure 2B is 6 microns, and the distance D1 is 3 microns, and when the optical switch element 1a is illuminated (for example, ultraviolet light UV, wavelength 375nm), its gate The characteristic curve of electrode voltage and drain current. In addition, in Fig. 4B, the distance 8/3 (dark) indicates that the offset distance D2 of Fig. 2B is 8 microns, and the distance D1 is 3 microns, and when the optical switching element 1a is not illuminated, its gate voltage and drain The characteristic curve of pole current. In addition, the distance 8/3 (bright) indicates that the offset distance D2 in Figure 2B is 8 microns, and the distance D1 is 3 microns, and when the optical switch element 1a is illuminated (for example, ultraviolet light UV, wavelength 375nm), its gate The characteristic curve of electrode voltage and drain current.

As shown in FIG. 4A and FIG. 4B, since the second electrode 15 of the optical switch element 1a is in the projection direction of the optical switch element 1a, the contact region C2 in contact with the channel layer 13 does not overlap with the gate 12 and has an offset. Therefore, the output current characteristics of the optical switching element 1a will become more and more distant from the controllable range of the gate 12 as the channel layer 13 (metal oxide semiconductor) increases with the increase of the offset distance D2. Therefore, under the same light irradiation conditions and electrical conditions, the non-overlapping area between the contact region C2 and the gate 12 cannot be effectively controlled by the voltage of the gate 12, and the connection between the source and the drain The amount of passing current between them will become smaller and smaller as the offset distance D2 increases. Therefore, when no light is irradiated, although the voltage of the gate 12 is input, the optical switch element 1a cannot be effectively controlled, that is, there is no way to allow sufficient current to pass through the first electrode 14 and the second electrode 15, as shown by the no-light curve in FIG. 4B Show.

However, as shown in the curves of distance 6/3 (bright) and distance 8/3 (bright) in FIG. 4A and FIG. When the metal oxide semiconductor in the non-overlapping area between the grid 12 and the metal oxide semiconductor is irradiated with light, under the same grid 12 voltage, since the metal oxide semiconductor will generate a large number of electron-hole pairs when it is illuminated, the current can pass through this bias. The region shifted by the distance D2 (the non-overlapping region), thereby significantly increasing the drain current. In this embodiment, an NMOS transistor with a positive voltage applied between the gate 12 and the drain is taken as an example. However, in other embodiments, a negative voltage bias can be applied to a PMOS transistor, depending on the transistor. Depends on the type.

In addition, please refer to FIG. 5A and FIG. 5B respectively, in which, FIG. 5A shows the drain current of the optical switch element 1a of the present invention when it is irradiated with ultraviolet light (375nm) and not irradiated with a bias voltage. 5B is a schematic diagram of the change of the drain current and time of the optical switch element 1a of the present invention when it is irradiated with blue light (470nm) and not irradiated with blue light. Therefore, during measurement, the voltage of the gate 12 is fixed at 2 volts, and the voltage of the drain is fixed at 10 volts.

As shown in Fig. 5A, when the optical switching element 1a is in a biased state and irradiated with ultraviolet light, its output drain current is increased by about 10 ⁴ to 10 ⁵ times compared with that without ultraviolet light, and when the ultraviolet light is turned off Afterwards, the drain current quickly returns to the original state. Therefore, the light-sensing state can be easily judged by the difference of the drain current, that is, there is a higher current through when the light is illuminated, and only a lower current when the light is not illuminated. Controlled by the difference characteristics, the optical switch element 1a can become a good optical switch or optical sensor. In addition, as shown in FIG. 5B , when the optical switch element 1 a is irradiated with blue light and not irradiated with blue light, its drain current still has a significant difference, and the difference ratio is about 10-100 times. In addition, compared with blue light irradiation, the drain current of the optical switching element 1a when irradiated with ultraviolet light is more than ¹⁰³ times greater than that when irradiated with blue light, so it can be applied to identify the design of different wavelengths of light .

In addition, a display panel according to a preferred embodiment of the present invention includes at least one optical switch element, and the optical switch element has a gate, a channel layer, at least one dielectric layer, a first electrode and a second electrode. The gate is disposed on the substrate. The channel layer is disposed on the substrate, and the channel layer is an oxide semiconductor. The dielectric layer is disposed between the gate and the channel layer. The first electrode is disposed on the channel layer and is in contact with the channel layer. The second electrode is arranged on the channel layer and contacts with the channel layer to have a contact area, and there is a space between the second electrode and the first electrode. There is an offset distance between the contact area and the gate in the projection direction of the optical switch element. Wherein, the optical switch element may be one of the above optical switch elements 1, 1a, 1b, and the optical switch elements 1, 1a, 1b have been described in detail above, and will not be repeated here. In practice, when there are multiple optical switch elements, multiple optical switch elements can be fabricated on the same substrate.

The display panel of the present invention can be a liquid crystal display panel or an OLED display panel. Wherein, if it is a liquid crystal display panel, the optical switch element can be fabricated on one of the two substrates in the display panel. Here, the optical switch element is not limited to be arranged on the thin film transistor substrate or the color filter. The substrate, or the color filter layer is arranged on the substrate on the side of the thin film transistor substrate (color filter on array). In one embodiment, the optical switch element can be fabricated on the thin film transistor substrate. The optical switching element and the driving element of the thin film transistor substrate can be manufactured using the same thin film transistor process, so that the liquid crystal display panel not only has the function of displaying images, but also has the function of light sensing or light switching. In addition, if the display panel is an OLED display panel, the optical switch element can be fabricated on the OLED display panel. The optical switching element and the driving element of the OLED substrate can be manufactured using the same thin film transistor process, so that the OLED display panel not only has the function of displaying images, but also has the function of light sensing or light switching. Of course, if the display panel with the optical switch element of the present invention is combined with a touch panel, the combined touch display panel can not only have the functions of display and touch, but also have the function of light sensing.

In addition, the light-sensing element and display panel of the present invention can be applied to any electronic equipment, such as light detection of televisions, light-sensitive detection of clocks or watches, detection of ultraviolet light or X-rays of medical equipment, electronic games or 3C products. Light detection, or other electronic devices that detect light for control purposes.

In summary, because the display panel of the present invention includes at least one optical switch element, the grid of the optical switch element is disposed on the substrate, the channel layer is disposed on the substrate, the channel layer is an oxide semiconductor, and the dielectric layer It is arranged between the gate and the channel layer. In addition, the first electrode is disposed on the channel layer and is in contact with the channel layer, and the second electrode is disposed on the channel layer and is in contact with the channel layer to have a contact area. In addition, there is an offset distance between the contact area and the gate in the projection direction of the optical switch element. In addition, the present invention enables the optical switching element and the driving element of the display panel to be manufactured using the same thin film transistor process, so the optical switching element can be integrated into the process of the display panel, thus not only does not introduce other materials to increase the cost of the process, It is also possible to increase the added value of the display panel.

The above descriptions are illustrative only, not restrictive. Any equivalent modification or change made without departing from the spirit and scope of the present invention shall be included in the patent scope of this application.

Claims (10)

1. An optical switch element, characterized in that, comprising: a substrate; a gate disposed on the substrate; A channel layer, disposed on the substrate, the channel layer is an oxide semiconductor; at least one dielectric layer disposed between the gate and the channel layer; a first electrode disposed on the channel layer and in contact with the channel layer; and A second electrode is arranged on the channel layer and is in contact with the channel layer to have a contact area, there is a gap between the second electrode and the first electrode, and the optical switch element In the projection direction, there is an offset distance between the contact region and the gate. 2. The optical switch device according to claim 1, wherein the oxide semiconductor comprises a metal oxide, and the metal oxide comprises at least one of indium, zinc, gallium, tin and hafnium. 3 . The optical switch element according to claim 1 , wherein a central plane of the grid extends through the channel layer, and the structure of the channel layer located on both sides of the central plane is asymmetric. 4 . 4. The optical switch element according to claim 1, wherein the offset distance is between 2 microns and 20 microns. 5 . The optical switch element according to claim 1 , wherein the optical switch element can sense a light, and the wavelength of the light is between 0.01 nm and 500 nm. 6. A display panel, characterized in that it comprises: at least one optical switching element having: a substrate; a gate disposed on the substrate; A channel layer, disposed on the substrate, the channel layer is an oxide semiconductor; at least one dielectric layer disposed between the gate and the channel layer; a first electrode disposed on the channel layer and in contact with the channel layer; and A second electrode is arranged on the channel layer and is in contact with the channel layer to have a contact area, there is a gap between the second electrode and the first electrode, and the optical switch element In the projection direction, the contact region and the gate have an offset distance. 7. The display panel according to claim 6, wherein the oxide semiconductor comprises a metal oxide, and the metal oxide comprises at least one of indium, zinc, gallium, tin and hafnium. 8 . The display panel according to claim 6 , wherein a center plane of the grid extends through the channel layer, and the structure of the channel layer on both sides of the center plane is asymmetric. 9. The display panel according to claim 6, wherein the offset distance is between 2 microns and 20 microns. 10 . The display panel according to claim 6 , wherein the optical switch element can sense a light, and the wavelength of the light is between 0.01 nm and 500 nm. 11 .