KR20220010084A - Optical sensor including 2-dimensional insulator - Google Patents

Abstract

The present application provides an optical sensor including a substrate, a two-dimensional material semiconductor layer formed on the substrate, a tunneling layer formed on the semiconductor layer, and first and second electrodes respectively disposed on both ends of the upper surface of the tunneling layer. The tunneling layer includes a two-dimensional insulator material containing energy trap defects.

Description

Optical sensor including two-dimensional insulator {OPTICAL SENSOR INCLUDING 2-DIMENSIONAL INSULATOR}

The present application relates to an optical sensor comprising a two-dimensional insulator.

Recently, as technologies such as mobile payment have been commercialized, security technologies are developing. As such a security technology, biometrics such as iris recognition are being studied.

In the case of a silicon-based image sensor currently commercially available, quantum efficiency for near-infrared (NIR) wavelengths of 800 nm to 900 nm is about 30%. Since the quantum efficiency of the near-infrared region is about 1/2 to 1/3 of that of the visible light band, the low-illuminance sensitivity of the image sensor is deteriorated. Accordingly, when iris authentication is performed with the image sensor in a low light environment, an additional light source is required because the sensitivity of the image sensor is low. However, there is a problem in that there is a risk of damage to the eyeball when a light source of high power is used.

In the case of LiDAR, 3D sensor, and low light sensor, high photoelectric conversion efficiency is required because a small light signal needs to be detected. In the case of the conventional silicon-based image sensor, the thickness of the silicon needs to be increased in order to increase the sensitivity to low light, and thereby, the pixel size increases, and thus there is a problem in that the size of the camera including the image sensor increases.

On the other hand, in order to mount a sensor for diagnosing blood sugar in a m-health device, an optical sensor capable of detecting a phonon of a target material without a spectrometer in accordance with the infrared region is required, but in the infrared region Since the conventional optical sensor requires a cooling system and thus increases the system volume, there is a problem in that it is difficult to be used in a mobile health device or the like.

In this regard, although the development of a next-generation optical sensor based on a two-dimensional material is attracting attention, there is a problem in that it is very difficult to control the device characteristics of the two-dimensional-based optical sensor. Graphene, which has been widely studied as a conventional two-dimensional material, has problems in that it responds equally to almost all wavelengths, so there is no reaction wavelength selectivity, and the light efficiency is low, so the reactivity is also low.

In this regard, in recent years, a lot of research has been done in relation to the development of an optical device using a transition metal dichalcogenides (TMDC) material, which has a very excellent light absorption compared to a unit thickness. However, a sensor structure with good photo-responsivity, dark current, and response time is extremely limited. Accordingly, there is a need for a sensor having improved light reactivity, dark current and response time characteristics.

Republic of Korea Patent Publication No. 10-2019-0097981, which is the background technology of the present application, relates to a near-infrared sensor including a two-dimensional insulator, and specifically, a two-dimensional material semiconductor layer on a substrate, a tunneling layer on the two-dimensional material semiconductor layer, and , a first electrode and a second electrode respectively disposed on both ends of an upper surface of the tunneling layer, wherein the semiconductor layer is a transition metal dichalcogenide having a thickness of approximately 10 nm to 100 nm, and the tunneling layer and the substrate are hBN It relates to a near-infrared sensor made of a material. However, the patent does not mention a photosensor including a two-dimensional insulator material including an energy trap defect and hardly generates a dark current because there are very few defect states inside the bandgap of the tunneling layer 130. is not

The present application is to solve the problems of the prior art, and an object of the present application is to provide an optical sensor including a two-dimensional insulator.

Another object of the present application is to provide an optoelectronic device including the photosensor.

However, the technical problems to be achieved by the embodiments of the present application are not limited to the technical problems described above, and other technical problems may exist.

As a technical means for achieving the above technical problem, the first aspect of the present application is disposed on both ends of a substrate, a two-dimensional material semiconductor layer formed on the substrate, a tunneling layer formed on the semiconductor layer, and an upper surface of the tunneling layer, respectively In the photosensor including a first electrode and a second electrode, the tunneling layer provides a photosensor comprising a two-dimensional insulator material containing energy trap defects.

According to the exemplary embodiment of the present application, the photosensor may selectively express a photogating phenomenon by confining holes or charges in the energy trap defect, but is not limited thereto.

According to an exemplary embodiment of the present disclosure, the photosensor may selectively control a positive photocurrent and a negative photocurrent according to a gate voltage, but is not limited thereto.

According to one embodiment of the present application, the substrate _{may include a material selected from the group consisting of SiO 2} /Si, hBN, polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), and combinations thereof. However, the present invention is not limited thereto.

According to one embodiment of the present application, the semiconductor layer may include a transition metal dichalcogenide, but is not limited thereto.

According to one embodiment of the present application, the transition metal dichalcogenide is MoTe ₂ , MoS ₂ , MoSe ₂ , WS ₂ , WSe ₂ , WTe ₂ , ZrS ₂ , ZrSe ₂ , HfS ₂ , HfSe ₂ , NbSe ₂ , ReSe ₂ , CuS, and may include one selected from the group consisting of combinations thereof, but is not limited thereto.

According to one embodiment of the present application, the semiconductor layer may have a thickness of 10 nm to 100 nm, but is not limited thereto.

According to one embodiment of the present application, the two-dimensional insulator material may include one selected from the group consisting of hexagonal boron nitride (hBN), alumina, hafnium oxide, and combinations thereof, but is not limited thereto. .

According to one embodiment of the present application, it may further include nanoparticles formed on the upper surface of the semiconductor layer, but is not limited thereto.

According to one embodiment of the present application, it may further include nanoparticles formed on the upper surface of the tunneling layer, but is not limited thereto.

According to one embodiment of the present application, the nanoparticles _{may include one selected from the group consisting of SiO 2} , SiN _x and combinations thereof, but is not limited thereto.

According to the exemplary embodiment of the present application, the first electrode and the second electrode may include a general metal or a transparent conductive oxide, but is not limited thereto.

According to one embodiment of the present application, the general metal may include, but is not limited to, one selected from the group consisting of Au, Al, Cu, Ti, Pt, Ag, Cr, and combinations thereof.

According to the exemplary embodiment of the present application, the transparent conductive oxide includes indium tin oxide (ITO), indium zinc oxide (IZO), ZnO, SnO ₂ , antimony-doped tin oxide (ATO), Al-doped zinc oxide (AZO), It may include one selected from the group consisting of gallium-doped zinc oxide (GZO), TiO ₂ , fluorine-doped tin oxide (FTO), and combinations thereof, but is not limited thereto.

A second aspect of the present application provides an optoelectronic device including the photosensor according to the first aspect of the present application.

The above-described problem solving means are merely exemplary, and should not be construed as limiting the present application. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description.

According to the above-described problem solving means of the present application, the optical sensor including the two-dimensional insulator according to the present application can provide a new optical sensor capable of controlling the polarity of the photocurrent by selectively expressing only the photogating phenomenon.

In the conventional photosensor operation, many photocurrent generating mechanisms such as photoconductivity, bolometric effect, and photogating effect exist in a complex manner, and there is a limitation in that only the function of increasing the current when irradiated with light is utilized. The photosensor including a two-dimensional insulator according to the present application uses a tunneling layer including a two-dimensional insulator material including an energy trap defect, thereby confining holes or charges in the energy trap defect to selectively express a photogating phenomenon. Therefore, it is possible to provide an optical sensor capable of selectively controlling a positive photocurrent and a negative photocurrent according to a gate voltage, which is beyond the limit of the existing optical sensor operation method.

In addition, by using a tunneling layer containing a two-dimensional insulator material containing an energy trap defect as a tunneling barrier between the electrode and the semiconductor layer, the dark current can be lowered, and the photoreactivity that can measure even weak light is improved. An improved optical sensor may be provided.

In addition, by using a semiconductor layer containing a transition metal dichalcogenide having an increased light absorption, the photoreactivity can be improved, and a wide range of optical sensors capable of detecting even light in the near-infrared region can be provided.

In addition, when using the conventional photogating phenomenon, it can have high photoresponse, but there is a limitation in that the switching time is very slow because it is a phenomenon mediated by electrons or holes trapped in an energy trap. The photosensor including: by changing the energy band bending direction of the semiconductor channel material by an energy trap defect in hBN to control the movement of photoelectrons, it is possible to quickly switch using electron mobility (mobility). Accordingly, it is possible to provide an optical sensor capable of realizing a fast switching time with high photoresponse.

In addition, since the photoelectric device according to the present application includes a photosensor using a relatively thin semiconductor layer, there is an advantage in miniaturization.

However, the effects obtainable herein are not limited to the above-described effects, and other effects may exist.

1 is a schematic diagram of an optical sensor according to an embodiment of the present application.
2 is a schematic diagram illustrating an operating principle of an optical sensor according to an embodiment of the present application.
3 is a schematic diagram illustrating a photocurrent polarity control principle of a photosensor according to an embodiment of the present application.
4 is a schematic diagram of a photosensor in which nanoparticles are deposited according to an embodiment of the present application.
5 is a graph showing a result of measuring the photoresponse of the photosensor according to the embodiment of the present application.
6 is a graph showing a result of measuring a switching time of an optical sensor according to an embodiment of the present application.
7 is a graph showing a current-gating voltage curve of the photosensor according to an embodiment of the present application.
8 is a graph showing a current-gating voltage curve at various wavelengths of the photosensor according to an embodiment of the present application.
9 is a graph showing a photocurrent-gate bias curve of the photosensor according to an embodiment of the present application.

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present application pertains can easily carry out. However, the present application may be implemented in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present application in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another element interposed therebetween. do.

Throughout this specification, when a member is positioned “on”, “on”, “on”, “on”, “under”, “under”, or “under” another member, this means that a member is positioned on the other member. It includes not only the case where they are in contact, but also the case where another member exists between two members.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to the numerical value when the manufacturing and material tolerances inherent in the stated meaning are presented, and to aid in the understanding of the present application. It is used to prevent an unconscionable infringer from using the mentioned disclosure in an unreasonable way. Also, throughout this specification, "step to" or "step to" does not mean "step for".

Throughout this specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It is meant to include one or more selected from the group consisting of.

Throughout this specification, reference to “A and/or B” means “A, B, or A and B”.

Hereinafter, the optical sensor including the two-dimensional insulator of the present application will be described in detail with reference to embodiments, examples, and drawings. However, the present application is not limited to these embodiments and examples and drawings.

As a technical means for achieving the above technical problem, the first aspect of the present application is a substrate 110 , a two-dimensional material semiconductor layer 120 formed on the substrate 110 , and formed on the semiconductor layer 120 . In the optical sensor 100 including a tunneling layer 130 and a first electrode 141 and a second electrode 142 respectively disposed on both ends of the upper surface of the tunneling layer 130, the tunneling layer 130 is Provided is a photosensor 100 comprising a two-dimensional insulator material containing energy trap defects.

Energy trap defects are defects that can occur in materials during material synthesis or device processing. These defects can be located at specific energy levels to trap positive and/or negative charges. The energy trap defects may exist in different energy level states locally, which may serve as a local gate. Therefore, there is an advantage in that the photocurrent characteristics can be controlled by effectively controlling the resistance of the material through charge induction in the channel semiconductor material by using the energy trap defect.

1 is a schematic diagram of an optical sensor 100 according to an embodiment of the present application, and FIG. 2 is a schematic diagram illustrating an operating principle of the optical sensor 100 according to an embodiment of the present application.

According to the exemplary embodiment of the present application, the photosensor 100 may selectively express a photogating phenomenon by confining holes or electric charges in the energy trap defect, but is not limited thereto.

In the conventional photosensor operation, many photocurrent generating mechanisms such as photoconductivity, bolometric effect, and photogating effect exist in a complex manner, and there is a limitation in that only the function of increasing the current when irradiated with light is utilized.

As will be described later, the photosensor 100 including a two-dimensional insulator according to the present application uses a tunneling layer 130 including a two-dimensional insulator material including an energy trap defect, thereby trapping holes or charges in the energy trap defect. Only the photogating phenomenon is selectively expressed. Therefore, it is possible to provide a new optical sensor 100 capable of controlling the polarity of a photocurrent that exceeds the limit of the existing optical sensor operation method.

According to the exemplary embodiment of the present disclosure, the photosensor 100 may selectively control a positive photocurrent and a negative photocurrent according to a gate voltage, but is not limited thereto.

According to one embodiment of the present application, the substrate 110 is SiO ₂ /Si, hBN, PET (polyethylene terephthalate), polydimethylsiloxane (polydimethylsiloxane, PDMS), and to include one selected from the group consisting of combinations thereof However, the present invention is not limited thereto.

For example, the substrate 110 may be SiO ₂ /Si, but is not limited thereto.

According to one embodiment of the present application, the semiconductor layer 120 may include a transition metal dichalcogenide, but is not limited thereto.

Referring to FIG. 1 , light may be irradiated onto the tunneling layer 130 between the first electrode 141 and the second electrode 142 . The two-dimensional material semiconductor layer 120 generates carriers when it receives near-infrared rays in a wavelength range of about 800 nm to 900 nm. The two-dimensional material semiconductor layer 120 serves as a channel for the carrier. The two-dimensional material semiconductor layer 120 is a layer that receives light and converts it into an electrical signal.

In the photosensor 100 including the two-dimensional insulator according to the present application, the photoreactivity may be improved by using the semiconductor layer 120 including the transition metal dichalcogenide having an increased light absorption. In addition, the transition metal dichalcogenide has a band gap of about 1 eV that can absorb near-infrared well, so that it can detect even light in the visible region to the light in the near-infrared region. can provide

According to one embodiment of the present application, the transition metal dichalcogenide is MoTe ₂ , MoS ₂ , MoSe ₂ , WS ₂ , WSe ₂ , WTe ₂ , ZrS ₂ , ZrSe ₂ , HfS ₂ , HfSe ₂ , NbSe ₂ , ReSe ₂ , CuS, and may include one selected from the group consisting of combinations thereof, but is not limited thereto.

Preferably, the transition metal dichalcogenide may be MoTe ₂ , but is not limited thereto.

_{MoTe 2, which} is a representative two-dimensional semiconductor material, has a bandgap energy of about 0.9 eV that can absorb near infrared rays well. Accordingly, the photosensor 100 including the two-dimensional insulator according to the present disclosure may detect light in the visible region to light in the near-infrared region.

According to one embodiment of the present application, the semiconductor layer 120 may have a thickness of about 10 nm to about 100 nm, but is not limited thereto.

If the thickness of the two-dimensional material semiconductor layer 120 is thinner than about 10 nm, the amount of light absorption is small, so it is difficult for the optical sensor 100 including the two-dimensional material semiconductor layer 120 to act as a sensor. If the thickness of the two-dimensional material semiconductor layer 120 is greater than about 100 nm, the size of the sensor increases, and thus it cannot be used as the small photosensor 100 .

For example, the semiconductor layer 120 may have a thickness of about 20 nm to about 50 nm, but is not limited thereto.

In the case of LiDAR, 3D sensor, and low light sensor, high photoelectric conversion efficiency is required because a small light signal needs to be detected. In the case of the conventional silicon-based image sensor, the thickness of the silicon needs to be increased in order to increase the sensitivity to low light, and thereby, the pixel size increases, so there is a problem in that the size of the camera including the image sensor increases.

In addition, in order to mount a sensor for diagnosing blood sugar, etc. in a mobile health device, an optical sensor capable of detecting a phonon of a target material without a spectrometer in accordance with the infrared region (IR) is required. Since the area optical sensor requires a cooling system and thus increases the system volume, there is a problem in that it is difficult to be used in a mobile health device or the like.

The photosensor 100 including a two-dimensional insulator according to the present application has an advantage that can be utilized as a small photosensor 100 by using a relatively thin semiconductor layer 120 .

The photosensor 100 including a two-dimensional insulator according to the present application uses a tunneling layer 130 including a two-dimensional insulator material including an energy trap defect, thereby confining holes or charges in the energy trap defect to form a photogating phenomenon. only selectively expressed. Therefore, it is possible to provide a new optical sensor 100 capable of controlling the polarity of a photocurrent that exceeds the limit of the existing optical sensor operation method.

According to one embodiment of the present application, the two-dimensional insulator material may include one selected from the group consisting of hexagonal boron nitride (hBN), alumina, hafnium oxide, and combinations thereof, but is not limited thereto. .

Preferably, the two-dimensional insulator material may be hBN, but is not limited thereto. hBN is an ideal two-dimensional insulator material, has excellent stability and can apply large-area expansion technology.

When the tunneling layer 130 is formed of hBN, an increase in current caused by excitons composed of electron-holes can be suppressed by increasing the contact resistance of the electrode. That is, the hBN tunneling layer 130 may have defect states inside the bandgap, thereby suppressing photoconductivity due to excitons.

Specifically, it is possible to trap holes or charges in a shallow energy trap defect present in hBN, and the trapped holes or charges are sufficient to change the conductivity of the semiconductor layer 120 including the transition metal dichalcogenide. electrons can be induced.

3 is a schematic diagram illustrating a photocurrent polarity control principle of the photosensor 100 according to an embodiment of the present application.

Referring to FIG. 3 , the bending direction is changed to the downward bending direction by covering _{the MoTe 2} that is originally bent upward toward the surface with hBN containing positive charge defects. This is because the positive charge defect of hBN _{induces electrons to the surface of MoTe 2} to control the direction of the electric field. Due to the electromagnetic induction, _{the bending direction of MoTe 2} in the dark state changes from top to bottom. This means that the electron energy level of the surface MoTe _{2 is the lowest.}

At this time, the main surface broiling light in the optoelectronic MoTe ₂ - hole pairs (electron hole pairs) are generated, with the top layer of the optoelectronic MoTe ₂ is moved. This means that the photoelectrons move to the lowest energy level. Due to this _{, the uppermost layer of MoTe 2} is very crowded with electrons, which completely hides the positive charge in hBN, so that the electric field in _{MoTe 2 disappears.} Therefore, photoconductivity is suppressed and only photogating can occur selectively. That is, electrons are induced by trapped holes or charges, strong band bending of the transition metal dichalcogenide is induced, and photoconductivity by excitons is induced. can develop a lowering selective photogating phenomenon.

Therefore, the photosensor 100 including the two-dimensional insulator according to the present application can control the polarity of the photocurrent through selective photogating control, so it can serve as a selection element to obtain a positive photocurrent or a negative photocurrent according to the gating voltage. There are advantages that can be

According to one embodiment of the present application, it may further include nanoparticles formed on the upper surface of the semiconductor layer, but is not limited thereto.

According to one embodiment of the present application, it may further include nanoparticles formed on the upper surface of the tunneling layer, but is not limited thereto.

According to the exemplary embodiment of the present application, the nanoparticles may include, but are not limited to, those selected from the group consisting _{of SiO 2} , SiN _{x and combinations thereof.}

4 is a schematic diagram of the photosensor 100 in which nanoparticles are deposited according to an embodiment of the present application.

_{When SiO 2} , SiN _x nanoparticles, or a thin film, etc. serving as a positive charge are placed on the semiconductor layer 120 , the direction of the band of _{MoTe 2 may be changed downward by the positive charge.} Due to this, only the photogating phenomenon can be selectively expressed.

In the case of (A) of Fig. 4, as compared with the 4 (B) is SiO _2, SiN _x nanoparticles or thin film exist at a relatively distant position as MoTe _2, to change the direction of the band MoTe ₂ to a smaller size can This is because as the distance increases, the strength of the electric field decreases, so the amount of electron induction inside the _{MoTe 2 layer decreases.}

In addition, the photosensor 100 including the two-dimensional insulator according to the present application uses the tunneling layer 130 including the two-dimensional insulator material including the energy trap defect as a tunneling barrier between the electrode and the semiconductor layer 120 . By doing so, there is an advantage in that it is possible to lower a dark current and provide the photosensor 100 with improved photoreactivity capable of measuring even weak light.

In addition, when using the conventional photogating phenomenon, it can have high photoresponse, but there is a limitation in that the switching time is very slow because it is a phenomenon mediated by electrons or holes trapped in an energy trap. The photosensor including: by changing the energy band bending direction of the semiconductor channel material by an energy trap defect in hBN to control the movement of photoelectrons, it is possible to quickly switch using electron mobility (mobility). Accordingly, there is an advantage in that it is possible to provide an optical sensor capable of implementing a fast switching time with high photoresponse.

The thickness of the tunneling layer 130 may be about 1 nm to 50 nm. When the thickness of the tunneling layer 130 is less than about 1 nm, the dark current may increase. When the thickness of the tunneling layer 130 is greater than about 50 nm, the tunneling current is small, so that the detection sensitivity of light may be reduced.

According to the exemplary embodiment of the present application, the first electrode 141 and the second electrode 142 may include a general metal or a transparent conductive oxide, but is not limited thereto.

According to one embodiment of the present application, the general metal may include, but is not limited to, one selected from the group consisting of Au, Al, Cu, Ti, Pt, Ag, Cr, and combinations thereof.

Preferably, the general metal may be Au, but is not limited thereto.

According to the exemplary embodiment of the present application, the transparent conductive oxide includes indium tin oxide (ITO), indium zinc oxide (IZO), ZnO, SnO ₂ , antimony-doped tin oxide (ATO), Al-doped zinc oxide (AZO), It may include one selected from the group consisting of gallium-doped zinc oxide (GZO), TiO ₂ , fluorine-doped tin oxide (FTO), and combinations thereof, but is not limited thereto.

A second aspect of the present application provides an optoelectronic device including the photosensor 100 according to the first aspect of the present application.

With respect to the optoelectronic device of the second aspect of the present application, detailed descriptions of parts overlapping with the first aspect of the present application are omitted, but even if the description is omitted, the contents described in the first aspect of the present application are in the second aspect of the present application The same can be applied.

Since the photoelectric device according to the present application includes the photosensor 100 using a relatively thin semiconductor layer 120, there is an advantage in that it can be miniaturized.

[Example]

Using SiO ₂ /Si as a substrate, MoTe ₂ having a thickness of 7 nm was formed as a two-dimensional material semiconductor layer on the substrate. Then, 7 nm thick hBN was formed as a tunneling layer on the semiconductor layer.

Next, an energy trap defect was formed in the hBN by using a PMMA/PVA (Polymethyl methacrylate/Polyvinyl alcohol) chemical. Specifically, hBN was peeled on the PMMA/PVA-coated substrate. Then, PVA was dissolved in distilled water and covered on _{MoTe 2 .}

Next, Au electrodes were respectively disposed on both ends of the upper surface of the tunneling layer to prepare a photosensor including a two-dimensional insulator material.

[Experimental Example 1]

5 is a graph showing a result of measuring the photoresponse of the photosensor according to the embodiment of the present application.

Specifically, by applying a voltage through the first electrode and the second electrode of the photosensor according to the embodiment of the present application, the current flowing therebetween was measured. The currents in the dark environment and when irradiated with light (bright environment) were respectively measured, and the photocurrent was obtained by subtracting the two current values. The photoresponse was calculated by dividing the photocurrent by the light power. The photocurrent was measured using a total of five visible and near-infrared wavelengths (488 nm, 638 nm, 689 nm, 725 nm, and 811 nm), and the photoresponse was calculated.

FIG. 5 is a graph in which photoresponse is calculated through photocurrent values when the gate bias is 0 V and the voltage applied between both electrodes (source-drain bias) is -3 V. FIG.

Through this, it was confirmed that the optical sensor according to the present application had a high optical response of 20 A/W. This is a result of photoresponse under strong light, suggesting that photoresponsivity can be increased in light of weaker intensity.

[Experimental Example 2]

6 is a graph showing a result of measuring a switching time of an optical sensor according to an embodiment of the present application.

Specifically, while applying a constant voltage (3 V) between the first electrode and the second electrode of the photosensor according to the embodiment of the present application, light is irradiated at regular intervals through a light chopper, and the first electrode and The current flowing between the second electrodes was measured. The lower current (~3 nA) is the current in the dark state, and the higher current (~9 nA) is the current in the light state.

Through this, it was confirmed that the photosensor according to the present application has a fast switching time of 1 ms.

[Experimental Example 3]

7 is a graph showing the current-gating voltage curve of the photosensor according to the embodiment of the present application, FIG. 8 is a graph showing the current-gating voltage curve at various wavelengths of the photosensor according to the embodiment of the present application, and FIG. 9 is a graph showing a photocurrent-gate bias curve of the photosensor according to an embodiment of the present application.

Specifically, light was irradiated onto the upper surface of the photosensor, that is, the tunneling layer. After the irradiated light passed through the tunneling layer, electron-hole pairs were generated in the semiconductor layer. The generated electron-hole pairs were separated into electrons and holes. The separated electrons move to an electrode to which a relatively high potential voltage is applied among the first electrode and the second electrode, and the degree of doping between the semiconductor layers is different. Accordingly, a tunneling current passing through the tunneling layer was generated. By measuring the tunneling current, the amount of light in the corresponding pixel of the photosensor was analyzed.

_{More specifically, in FIG. 7 , the photocurrent (I PC} ) according to the voltage applied between the first electrode and the second electrode is measured in black in a dark environment and in red in a bright environment. Visible light at 689 nm was used.

In addition, a wavelength of 488 nm is used in (A) of FIG. 8, a wavelength of 638 nm in FIG. 8(B), a wavelength of 725 nm in FIG. 8(C), and a wavelength of 811 nm in FIG. 8(D).

In addition, FIG. 9 shows a current flowing therebetween by applying a voltage through the first electrode and the second electrode of the photosensor according to the embodiment of the present application. The currents in the dark environment and when irradiated with light (bright environment) were respectively measured, and the photocurrent was obtained by subtracting the two current values. The photocurrent was measured using a visible light wavelength (689 nm).

7 , it was confirmed that only the photogating phenomenon in which the current-voltage curve horizontally moves when light is irradiated occurs selectively. That is, it was confirmed that the polarity of the photocurrent could be controlled by selectively bringing a positive photocurrent (green region) or a negative photocurrent (blue region) according to the gate voltage.

Also, through FIG. 8 , it was confirmed that the photosensor according to the present application selectively secures a positive photocurrent and a negative photocurrent according to the gating control regardless of the wavelength, thereby controlling the polarity of the photocurrent. This is, since MoS ₂ has a bandgap energy of 0.9 eV (wavelength: 1378 nm), it is possible to control gating using light of a wavelength of 488 nm in the visible region to light of a wavelength of 811 nm in the near-infrared region, and this This suggests that gating control of up to -14 V is possible.

Also, through FIG. 9 , it was confirmed that the photosensor according to the present application selectively has a positive photocurrent and a negative photocurrent according to the gate voltage.

The above description of the present application is for illustration, and those of ordinary skill in the art to which the present application pertains will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present application.

100: light sensor
110: substrate
120: two-dimensional material semiconductor layer
130: tunneling layer
141: first electrode
142: second electrode

Claims (14)

Board;
a two-dimensional material semiconductor layer formed on the substrate;
a tunneling layer formed on the semiconductor layer; and
first and second electrodes respectively disposed on both ends of the upper surface of the tunneling layer;
In the optical sensor comprising a,
wherein the tunneling layer comprises a two-dimensional insulator material comprising energy trap defects.
light sensor.
The method of claim 1,
The photosensor is to selectively express a photogating phenomenon by trapping holes or charges in the energy trap defect.
The method of claim 1,
The photosensor is to selectively control the positive photocurrent and the negative photocurrent according to the gate voltage, the photosensor.
The method of claim 1,
Wherein the substrate comprises one _{selected from the group consisting of SiO 2} /Si, hBN, polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), and combinations thereof.
The method of claim 1,
The semiconductor layer will include a transition metal dichalcogenide, the photosensor.
6. The method of claim 5,
The transition metal dichalcogenide is MoTe ₂ , MoS ₂ , MoSe ₂ , WS ₂ , WSe ₂ , WTe ₂ , ZrS ₂ , ZrSe ₂ , HfS ₂ , HfSe ₂ , NbSe ₂ , ReSe ₂ , CuS and combinations thereof. Which comprises one selected from the group consisting of, an optical sensor.
The method of claim 1,
The semiconductor layer will have a thickness of 10 nm to 100 nm, the photosensor.
The method of claim 1,
wherein the two-dimensional insulator material comprises one selected from the group consisting of hexagonal boron nitride (hBN), alumina, hafnium oxide, and combinations thereof.
The method of claim 1,
The optical sensor further comprising nanoparticles formed on the upper surface of the semiconductor layer.
The method of claim 1,
The optical sensor further comprising nanoparticles formed on the upper surface of the tunneling layer.
The method of claim 1,
The first electrode and the second electrode will include a general metal or a transparent conductive oxide, the photosensor.
12. The method of claim 11,
The general metal will include one selected from the group consisting of Au, Al, Cu, Ti, Pt, Ag, Cr, and combinations thereof, the photosensor.
12. The method of claim 11,
The transparent conductive oxide includes indium tin oxide (ITO), indium zinc oxide (IZO), ZnO, SnO ₂ , antimony-doped tin oxide (ATO), Al-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO). , TiO ₂ , FTO (fluorine-doped tin oxide), and a photosensor comprising one selected from the group consisting of combinations thereof.
According to any one of claims 1 to 13, comprising an optical sensor according to any one of claims, an optoelectronic device.

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