TWI555217B - Optic detector - Google Patents

Description

Light detector and its operation

The invention relates to a photodetector, in particular to an adjustable photodetector.

Automation has become the mainstream trend of current technology development. In order to provide better environmental identification of the system, various detectors have been developed. Among them, light detectors that can detect bright and dark environments have a wide range of applications, such as switching for automatic lighting, brightness detection of mobile phones, and flashing.

However, different sources of light have different intensities. For different intensity of light, it is difficult for conventional photodetectors to satisfy different conditions with a single sensitivity. In addition, since light is an electromagnetic wave with multiple wavelengths superimposed, when it is necessary to specifically detect light in a certain interval, conventional photodetectors also need to face noise problems of different wavelengths. Therefore, how to solve the above problems has become an urgent problem to be solved in related fields.

The embodiment of the invention provides a photodetector, which can correspond to different environments. The sensitivity is changed by demand to achieve an adjustable effect. In addition, the use of different active layer materials can better detect the single-band light, making the light detector more accurate.

Embodiments of the present invention provide a photodetector including a substrate, a bottom gate electrode, a first insulating layer, an active layer, an electrode layer, a second insulating layer, and a top gate electrode. The bottom gate electrode is disposed on the substrate. The first insulating layer is disposed on the substrate and the bottom gate electrode. The active layer is disposed on the first insulating layer and on the bottom gate electrode. The active layer has an energy gap. The electrode layer is disposed on the active layer. The electrode layer includes a source electrode, a drain electrode, and an opening. The source electrode is connected to one side of the active layer. The drain electrode is connected to the other side of the active layer. The opening is between the source electrode and the drain electrode, wherein the active layer is exposed to the opening as a light receiving region. A second insulating layer is disposed on the electrode layer. The top gate electrode is disposed on the second insulating layer and located on the light receiving region.

According to one or more embodiments of the present invention, the photodetector further includes a barrier layer disposed between the active layer and the electrode layer. The barrier layer comprises perforations, wherein the perforations are respectively located on opposite sides of the active layer such that the source electrode and the drain electrode are connected to the active layer through the perforations.

According to one or more embodiments of the present invention, the second insulating layer, the barrier layer, and the top gate electrode are translucent.

According to one or more embodiments of the invention, the active layer is a metal oxide layer.

According to one or more embodiments of the present invention, the metal oxide layer material is indium gallium zinc oxide (IGZO), indium gallium zinc oxide (IZO), gallium oxide (IGO), gallium zinc oxide (GZO), zinc. Oxide (ZnO), indium oxide (InO), aluminum zinc oxide (AZO) or a combination thereof.

According to one or more embodiments of the present invention, the width of the top gate electrode is smaller than the width of the light receiving region and the opening, respectively.

The invention provides a mode of operation of the photodetector, comprising applying a first bias voltage to the gate electrode for generating a potential barrier, and the potential barrier acts as a limiting carrier. After the active layer is excited by the light of the predetermined band, the potential barrier is lowered and a carrier channel is generated. A second bias voltage is applied to the other gate electrode for generating an amplified current.

According to one or more embodiments of the invention, the predetermined band is determined by the active layer material.

According to one or more embodiments of the present invention, the predetermined wavelength band is an ultraviolet light band, and the active layer material is indium gallium zinc oxide (IGZO), indium oxide (InO3), tin oxide (SnO2), zinc oxide (ZnO). ) or a combination thereof.

According to one or more embodiments of the present invention, the operation of the photodetector further includes adjusting a second bias voltage for controlling the amplification current and applying a starting voltage to the drain electrode for controlling the initial current.

The photodetector provided by the embodiment of the invention is an adjustable photodetector. In use, a bias voltage is input to the top gate electrode and the bottom gate electrode, and the sensitivity is controlled by the bias voltage. Moreover, for different predetermined active layer materials for the light of the predetermined band to be detected, the photodetector can detect the single band to achieve the distortion-free effect.

100‧‧‧Photodetector

102‧‧‧Substrate

104‧‧‧Bottom gate electrode

106‧‧‧First insulation

110‧‧‧ active layer

112‧‧‧electrode layer

113‧‧‧Source electrode

114‧‧‧汲electrode

116‧‧‧ openings

118‧‧‧Light receiving area

119‧‧‧Second insulation

120‧‧‧ top gate electrode

122‧‧‧Barrier

124‧‧‧Perforation

126‧‧‧Guiding layer

128‧‧‧ Guide column

130‧‧‧Light

140, 142, 144, 146‧‧‧ curves

S10~S50‧‧‧Steps

A, A’, B, B’, C, C’‧‧‧ data points

D‧‧‧ magnification ratio

Figure 1A is a front elevational view of a first embodiment of a photodetector in accordance with the present invention.

FIG. 1B is a schematic top view of the photodetector of FIG. 1A

2A is a front elevational view of a second embodiment of a photodetector in accordance with the present invention.

2B is a top plan view of the photodetector of FIG. 2A.

FIG. 3 is a flow chart of an embodiment of a method for operating a photodetector of the present invention.

4 is a flow chart of another embodiment of a method of operating a photodetector of the present invention.

Fig. 5 is a graph showing current and voltage curves in different operation modes of the photodetector of the present invention.

Figure 6 is a graph showing current and voltage of an embodiment of the operation mode of the photodetector of the present invention.

Figure 7 is a schematic diagram showing the operation of an embodiment of the photodetector of the present invention.

Fig. 8A is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 10 volts.

Fig. 8B is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 5 volts.

Figure 8C is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 1 volt.

Fig. 8D is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 0.1 volt.

Figure 9 is a front elevational view of a third embodiment of a photodetector in accordance with the present invention.

The spirit and scope of the present invention will be apparent from the following description of the preferred embodiments of the invention. The spirit and scope of the invention are not departed.

In view of the fact that the conventional photodetector only has a fixed light sensitivity, since the actual light intensity is not a single intensity, the detection result is distorted because the light sensitivity cannot be adjusted. In addition, when it is necessary to detect light in a certain band, the noise caused by light in other bands can also distort the detection result.

Therefore, the photodetector provided by the present invention adjusts the light sensitivity by controlling different top gate electrodes and bottom gate electrode bias combinations. Moreover, different active layer materials are used to detect specific single-band light to achieve more accurate detection.

Please refer to FIG. 1A, which is a front elevational view of a first embodiment of a photodetector in accordance with the present invention. The photodetector 100 includes a substrate 102, a bottom gate electrode 104, a first insulating layer 106, an active layer 110, an electrode layer 112, a second insulating layer 119, and a top gate electrode 120.

The bottom gate electrode 104 is disposed on the substrate 102. The first insulating layer 106 is disposed on the substrate 102 and the bottom gate electrode 104. The bottom gate electrode 104 on the substrate 102 is covered by the first insulating layer 106.

The active layer 110 is disposed on the first insulating layer 106 and on the bottom gate electrode 104. Wherein, in addition to being located above the bottom gate electrode 104, the active layer 110 and the bottom gate electrode 104 are cast on the substrate 102. The shadow area overlaps partially.

The material property of the active layer 110 is such that it has an energy gap, that is, after the active layer 110 absorbs light energy, an exciton is generated and separated into an electron hole-hole under appropriate conditions. Therefore, the active layer 110 material is preferably a semiconductor material.

For example, the active layer 110 may be a metal oxide layer made of indium gallium zinc oxide (IGZO), indium zinc oxide (IZO), indium gallium oxide (IGO), gallium zinc oxide (GZO), zinc. Oxide (ZnO), indium oxide (InO), aluminum zinc oxide (AZO), or a combination thereof.

Alternatively, the active layer 110 can be an organic semiconductor layer, the material of which includes, but is not limited to, an organic dye electrolyte, an organic polymer material, an organic small molecule material, or a donor/acceptor material commonly found in organic photovoltaics.

The electrode layer 112 is disposed on the active layer 110. The electrode layer 112 includes a source electrode 113, a drain electrode 114, and an opening 116. The source electrode 113 is connected to one side of the active layer 110, and the drain electrode 114 is connected to the other side of the active layer 110. The opening 116 is located between the source electrode 113 and the drain electrode 114 such that the source electrode 113 and the drain electrode 114 are connected to the active layer 110.

The materials of the bottom gate electrode 104, the source electrode 113 and the drain electrode 114 include, but are not limited to, titanium (Ti), aluminum (Al), molybdenum (Mo), silver (Ag), gold (Au), copper ( Cu), indium tin oxide (ITO), or a combination thereof.

The second insulating layer 119 is disposed on the electrode layer 112, and the top gate electrode 120 is disposed on the second insulating layer 119, wherein the second insulating layer 119 and the top gate electrode 120 are translucent. The second insulating layer 119 is located at the electrode Between the layer 112 and the top gate electrode 120, the effect of electrically isolating the electrode layer 112 and the top gate electrode 120 is provided.

The materials of the first insulating layer 106 and the second insulating layer 119 include, but are not limited to, cerium oxide (SiO ₂ ), cerium nitride (Si ₃ N ₄ ), cerium oxynitride (SiON), and aluminum oxide (Al ₂ O). ₃ ), an insulator material of an organic resin or a combination thereof.

Specifically, the source electrode 113 and the drain electrode 114 are electrically coupled to the active layer 110 , and at least a portion of the source electrode 113 and the drain electrode 114 may be located above the active layer 110 . The second insulating layer 119 and the top gate electrode 120 are located above the active layer 110. Moreover, since the second insulating layer 119 and the top gate electrode 120 have light transmissivity, the active layer 110 region exposed by the opening 116 between the source electrode 113 and the drain electrode 114 becomes a light receiving region 118.

In addition to this, the top gate electrode 120 is located above the light receiving region 118. Please refer to FIG. 1B. FIG. 1B is a schematic top view of the photodetector of FIG. 1A. The opening 116 is located between the source electrode 113 and the drain electrode 114, and the active layer 110 is exposed at the opening 116 as a light receiving region 118 (shaded portion in the figure).

The area of the light receiving region 118, the area of the bottom gate electrode (not shown) projected to the light receiving region 118, and the area projected by the top gate electrode 120 to the light receiving region 118 may at least partially overlap. The width of the top gate electrode 120 may be equal to or smaller than the width of the light receiving region 118 and the opening 116, respectively.

Please refer to both Figure 2A and Figure 2B. Figure 2A is based on A front view of a second embodiment of the photodetector of the present invention. 2B is a top plan view of the photodetector of FIG. 2A. The photodetector 100 includes a substrate 102, a bottom gate electrode 104, a first insulating layer 106, an active layer 110, a barrier layer 122, an electrode layer 112, a second insulating layer 119, and a top gate electrode 120. The electrode layer 112 includes a source electrode 113 and a drain electrode 114.

This embodiment is different from the first embodiment in that a barrier layer 122 is disposed between the active layer 110 and the electrode layer 112. The use of barrier layer 122 is an etch stop layer. When the photodetector 100 is fabricated, an etching process is required to define the shape of the source electrode 113 and the drain electrode 114, and the barrier layer 122 as an etch stop layer will protect the active layer 110 from damage during the etching process. The material of the barrier layer 122 is an insulator material of cerium oxide (SiO ₂ ), cerium nitride (Si ₃ N ₄ ), cerium oxynitride (SiON), aluminum oxide (Al ₂ O ₃ ), an organic resin, or a combination thereof.

The barrier layer 122 includes vias 124, wherein the vias 124 are respectively located on opposite sides of the active layer 110 such that the source electrode 113 and the drain electrode 114 are connected to the active layer 110 through the vias 124.

In addition, there is still an opening 116 between the source electrode 113 and the drain electrode 114 to define a region of the active layer 110 to which it is exposed as the light receiving region 118, such as the shaded region in FIG. 2B.

Refer to Figure 3. FIG. 3 is a flow chart of an embodiment of a method for operating a photodetector of the present invention. Step S10 is to apply a first bias voltage to the gate electrode for generating a potential barrier, and the potential barrier acts as a limiting carrier. In step S20, after the active layer is excited by the light of the predetermined wavelength band, the potential barrier is lowered, and the carrier channel is generated. Step S30 is to apply a second bias to the other gate electrode, Used to generate an amplified current.

Returning to FIG. 2A, the photodetector 100 of the present invention has a top gate electrode 120 and a bottom gate electrode 104, and the working mechanism can be controlled by applying a bias voltage to the top gate electrode 120 and the bottom gate electrode 104. . For example, a bias is applied to the top gate electrode 120 to define the switching state of the photodetector 100. That is, when the top gate electrode 120 is biased, the carrier channel provided by the active layer 110 is turned off so that the carrier cannot pass. This state is relative to step S10.

The "closed" referred to herein is such that the carrier channel is somewhat limited such that there is only a weak current between the source electrode 113 and the drain electrode 114, rather than indicating no current. When the carrier channel is not limited by this, the current is amplified several times, and the difference is defined as "off", which is described first.

Next, when the photodetector 100 is defined as being turned off, when the light ray 130 is incident on the light receiving region 118, the active layer 110 is excited by the light ray 130 to generate an electron hole pair, such that the source electrode 113 and the drain electrode 114 are interposed. There is a current flowing (far greater than the current when there is no light). This state is relative to step S20.

In the above case, by applying another bias voltage to the bottom gate electrode 104, the current between the source electrode 113 and the drain electrode 114 can be increased. This state is relative to step S30.

Please refer to FIG. 2A and FIG. 4 simultaneously. FIG. 4 is a flow chart of another embodiment of the method for operating the photodetector of the present invention. Step S10 is to apply a first bias voltage to the gate electrode for generating a potential barrier, and the potential barrier acts as a limiting carrier. Step S20 is to activate the main light by using the light of the predetermined band. After the moving layer, the potential barrier is lowered and a carrier channel is generated. Step S30 is to apply a second bias voltage to the other gate electrode for generating an amplification current. Step S40 is to adjust the second bias voltage to control the amplification current. Step S50 is to apply a starting voltage to the drain electrode for controlling the starting current.

Regardless of whether or not the photodetector 100 is illuminated, the magnitude of the current between the source electrode 113 and the drain electrode 114 can be adjusted by adjusting the bias voltage of the bottom gate electrode 104. In addition, in addition to adjusting the bias voltage of the bottom gate electrode 104 and applying a bias voltage to the gate electrode 114, the initial current of the photodetector 100 in the absence of illumination can be adjusted.

In summary, initially, the photodetector 100 of the present invention can operate on the presence or absence of light as a basis for operation. In the following, the second embodiment of the photodetector 100 is further adapted to the steps of the actual operation. instruction of. Wherein, since the predetermined detection band of the photodetector 100 is determined by the material of the active layer 110, the following actual operation of the predetermined detection band is exemplified by an ultraviolet band (ie, light having a wavelength of 300 nm to 450 nm). Accordingly, the corresponding active layer 110 material may comprise or be indium gallium zinc oxide (IGZO), indium oxide (InO ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), or a combination thereof. The use of indium gallium zinc oxide (IGZO), indium oxide (InO ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO) or a combination thereof as the active layer can increase the S/N ratio of the sensor.

However, it should be understood that the above-mentioned predetermined detection band is merely an exemplification, and is not intended to limit the present invention. Those having ordinary knowledge in the technical field of the present invention can flexibly select the material of the active layer 110 according to actual needs. To determine the predetermined detection band of the photodetector 100.

Please refer to Figure 2A and Figure 5 at the same time. Fig. 5 is a graph showing current and voltage curves in different operation modes of the photodetector of the present invention. In the figure, the vertical axis represents the magnitude of the current of the drain electrode 114, and the horizontal axis represents the voltage of the bottom electrode 101 of the bottom. The curve 140 is not biased (0 volts) corresponding to the top gate electrode 120 of the photodetector 100. Curve 142 is a bias voltage of -20 volts applied to top gate electrode 120 of photodetector 100. Curve 144 is a bias voltage of -40 volts applied to top gate electrode 120 of photodetector 100. In addition, the curves 140, 142, and 144 are all cases where no light is incident on the photodetector 100.

In the absence of illumination, when a bias voltage is applied to the top gate electrode 120, the photodetector 100 can be defined as a closed state. At this time, the magnitude of the voltage of the bottom gate electrode 104 is adjusted to drive and control the magnitude of the current between the source electrode 113 and the drain electrode 114. However, different top gate electrode 120 voltages have different effects.

For example, when the top gate electrode 120 is not biased, a voltage of substantially 0 volts or more is applied to the bottom gate electrode 104 to be driven, as shown by curve 140. When the top gate electrode 120 applies a bias voltage of -20 volts, the bottom gate electrode 104 needs to apply a voltage of approximately 10 volts or more to drive, such as curve 142. While a bias of -40 volts is applied to the top gate electrode 120, even if the bottom gate electrode 104 applies a voltage of 20 volts, it cannot be driven, as in curve 144.

That is to say, those skilled in the art to which the present invention pertains can flexibly select the bias voltages of the top gate electrode 120 and the bottom gate electrode 104 to define the switch shape of the photodetector 100. state.

Please refer to Figure 6. Figure 6 is a graph showing current and voltage of an embodiment of the operation mode of the photodetector of the present invention. The vertical axis is the magnitude of the drain electrode current, and the horizontal axis is the different bottom gate electrode voltage. In this embodiment, the top gate electrode of the photodetector is biased at -40 volts. Curve 144 is a corresponding light non-incident light detector, and curve 146 is an incident light detector corresponding to the light.

Taking the bottom gate electrode as a bias voltage of 5 volts, the drain electrode current of curve 146 is significantly greater than the drain electrode current of curve 144. The photodetector of the present invention uses the degree of change of the drain electrode current as a basis for detecting the presence or absence of illumination.

According to an embodiment of the invention, when the top gate electrode is -40 volts and the bottom gate electrode is about 0 volts, the data point A and the data point A' are taken as an example, the unlit data point A and the illuminated data Point A', the drain electrode currents differ by more than 10 ³ times. Under this bias setting, the carrier channel is off when there is no illumination, and the carrier channel is on when there is illumination, resulting in a significant amplification effect of the current. Therefore, the photodetector of the present invention is based on the on/off state of the carrier channel.

When the bottom gate electrode is increased to about 10 volts, taking the data point B and the data point B' as an example, the unpolarized data point B and the illuminated data point B' have a difference in the drain electrode current greater than ¹⁰⁶ times. Due to the increased bias of the bottom gate electrode, the transmission effect of the carrier channel is improved, resulting in a more significant amplification of the current. Similarly, the photodetector of the present invention can be used as a basis for the presence or absence of illumination depending on the on/off state of the carrier channel.

Or, when the bottom gate electrode is increased to about 20 volts, taking the data point C and the data point C' as an example, the un-lighted data point C and the illuminated data point C' have a difference in the drain electrode current greater than 10 ⁷ times. Therefore, when the bottom gate electrode is continuously increased, the photodetector of the present invention can also be based on the on/off state of the carrier channel as the basis for the presence or absence of illumination.

In summary of the above results, the present invention differs in the current amplification of the gate electrode by applying different bottom gate electrode biases, and thereby defines the light sensitivity of the photodetector as a switching state. More specifically, as long as the bottom gate electrode bias is adjusted, different current amplification effects can be obtained. Therefore, the photodetector of the present invention has an adjustable light sensitivity.

This effect can be applied to increase the bottom gate electrode bias when the ambient light is weak, and output a larger current to facilitate detection. Conversely, when the ambient gate light is strong, the bottom gate electrode bias is lowered, and a smaller current is output to prevent the carrier channel from being unintentionally turned on.

However, it should be understood that the above-mentioned bias combination of the top gate electrode and the bottom gate electrode is merely an example, and is not intended to limit the present invention, and those having ordinary knowledge in the technical field of the present invention may be required according to actual needs. The bias combination of the top gate electrode and the bottom gate electrode is elastically selected to define the light sensitivity of the photodetector.

Referring to FIG. 7, FIG. 7 is a schematic diagram showing the operation of an embodiment of the photodetector of the present invention. In this figure, the vertical axis is the drain electrode current and the horizontal axis is the time second. In this embodiment, the top gate electrode and the bottom gate electrode are biased at -40 volts and 20 volts, respectively. In addition, in this embodiment, a bias voltage of 10 volts is applied to the drain electrode, and the light source is used in a cycle of 50 seconds. Switching.

When there is no light, the drain electrode current is between 10 ^-15 amps and 10 ^-13 amps due to the carrier channel off (off), and when there is illumination, the carrier channel is turned on (on), the drain electrode current It is about 10 ^-6 amps. Therefore, the amplification ratio D of the two is at least ¹⁰⁶ times. In addition, since the switching state (on/off) of the carrier channel is switched rapidly, the current change is changed from no light (light) to light (no light). Through the above advantages, the photodetector of the present invention can achieve the effect of instant detection and high recognizability.

In addition, in addition to adjusting the bottom gate electrode bias to adjust the light sensitivity, the photodetector of the present invention can adjust the initial current of the drain electrode by different gate electrode biases.

For example, the top gate electrode and the bottom gate electrode are both -15 volts, and the following description will be made in conjunction with Figs. 8A to 8D. Fig. 8A is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 10 volts. Fig. 8B is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 5 volts. Figure 8C is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 1 volt. Fig. 8D is a schematic view showing the operation of the photodetector of the present invention with the gate electrode biased at 0.1 volt. The reference triangle is the incident light intensity of 5,700 lux (LUX), and the circular number is the incident light intensity of 1000 LUX.

When the drain electrode bias is 10 volts, the unilluminated current of the drain electrode is between about 10 ^-11 amps and 10 ^-12 amps. When the gate electrode bias is 5 volts, the unilluminated current of the drain electrode is approximately 10 ^-12 amps. When the drain electrode bias is 1 volt, the unilluminated current of the drain electrode is between about 10 ^-12 amps and 10 ^-13 amps. When the drain electrode bias is 0.1 volts, the unilluminated current of the drain electrode is between about 10 ^-12 amps and 10 ^-13 amps.

In the above case, when the light is not illuminated, a bias voltage is applied to the drain electrode so that the drain electrode has an initial current. Different bias voltages cause different starting currents. When illuminated, the drain electrode current is of course different. Therefore, the photodetector of the present invention can further define different light sensitivities by applying a bias voltage to the drain electrode. That is to say, those having ordinary knowledge in the technical field of the present invention can flexibly select the bias combination of the top gate electrode, the bottom gate electrode and the drain electrode according to actual needs to define the light sensitivity of the photodetector and Output current.

Please refer to FIG. 9. FIG. 9 is a front elevational view showing a third embodiment of the photodetector according to the present invention. The photodetector 100 includes a substrate 102, a bottom gate electrode 104, a first insulating layer 106, an active layer 110, a barrier layer 122, an electrode layer 112, a second insulating layer 119, a top gate electrode 120, and a guiding layer 126. The electrode layer 112 includes a source electrode 113 and a drain electrode 114, and an opening 116 is defined between the source electrode 113 and the drain electrode 114 to define a light receiving region 118.

The present embodiment is different from the second embodiment in that a guiding layer 126 is added to the opening 116 in the embodiment, and the guiding layer 126 is overlapped with the light receiving area 118, wherein the guiding layer 126 is defined by the guiding post 128. As such, when the light 130 enters the light receiving region 118, it will enter the active layer 110 through the pillars 128. The guide post 128 can be a nanoscale cylinder or a nanotube, or a micron scale. The pillars 128 can be materials having Z-axis growth characteristics including, but not limited to, zinc oxide (ZnO) or titanium dioxide (TiO ₂ ).

According to an embodiment of the invention, light rays 130 will be collected more efficiently on active layer 110 by pillars 128. More specifically, when the light ray 130 is reflected on the surface of the active layer 110, the conductive pillars 110 are scattered back to the active layer 110. According to the same mechanism, a nanohole or a nanowires (not shown) may be formed on the surface of the active layer 110, and the topography thereof enhances the ability of the active layer 110 to collect the light 130. To improve the detection efficiency of the photodetector 100 of the present invention.

In summary, the present invention provides a photodetector that defines a wavelength of a predetermined detection range by a material gap of an active layer such that wavelength light outside the range does not become noise and detects distortion. And, through a combination of bias voltages of different top gate electrodes and bottom gate electrodes, to define the required light sensitivity. In addition, the initial current of the drain electrode can be adjusted by setting the bias voltage of the drain electrode for more in-depth light sensitivity control.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100‧‧‧Photodetector

102‧‧‧Substrate

104‧‧‧Bottom gate electrode

106‧‧‧First insulation

110‧‧‧ active layer

112‧‧‧electrode layer

113‧‧‧Source electrode

114‧‧‧汲electrode

116‧‧‧ openings

118‧‧‧Light receiving area

119‧‧‧Second insulation

120‧‧‧ top gate electrode

122‧‧‧Barrier

124‧‧‧Perforation

130‧‧‧Incoming light

Claims (9)

A photodetector includes: a substrate; a bottom gate electrode disposed on the substrate; a first insulating layer disposed on the substrate and the bottom gate electrode; an active layer disposed on the first On the insulating layer, and on the bottom gate electrode, wherein the active layer is a metal oxide layer, and the active layer has an energy gap; an electrode layer is disposed on the active layer, and includes: a source electrode, Connected to one side of the active layer; a drain electrode connected to the other side of the active layer; and an opening between the source electrode and the drain electrode, wherein the active layer is exposed to the opening a light receiving region; a second insulating layer disposed on the electrode layer; and a top gate electrode disposed on the second insulating layer and located on the light receiving region. The photodetector of claim 1, further comprising a barrier layer disposed between the active layer and the electrode layer, the barrier layer comprising a plurality of perforations, wherein the perforations are respectively located in opposite sides of the active layer The side is such that the source electrode and the drain electrode are connected to the active layer through the through holes. The photodetector of claim 2, wherein the second insulating layer, the barrier layer, and the top gate electrode are translucent. The photodetector of claim 1, wherein the metal oxide layer material is indium gallium zinc oxide, indium zinc oxide, indium gallium oxide, gallium zinc oxide, zinc oxide, indium oxide, oxidation Aluminum zinc or a combination thereof. The photodetector of any one of claims 1 to 4, wherein the width of the top gate electrode is smaller than the width of the light receiving region and the opening, respectively. A method of operating a photodetector includes: applying a first bias voltage to a gate electrode for generating a potential barrier, the potential barrier acts as a limiting carrier; and exciting an active light with a predetermined wavelength band After the layer, the potential barrier is lowered and a carrier channel is generated; and a second bias voltage is applied to the other gate electrode for generating an amplification current. The mode of operation of the photodetector of claim 6, wherein the predetermined band is determined by the active layer material. The operation mode of the photodetector of claim 6, further comprising: adjusting the second bias voltage to control the amplification current; and applying a starting voltage to a drain electrode for controlling an initial current . The operation mode of the photodetector according to any one of claims 6 to 8, wherein the predetermined wavelength band is an ultraviolet light band, and the material of the active layer is indium gallium zinc oxide, indium oxide, tin oxide, Zinc oxide or a combination thereof.