阅读说明：本技术 一种具有低暗电流的自驱动型光电探测器及其制备方法 (Self-driven photoelectric detector with low dark current and preparation method thereof ) 是由 周长见 张首勇 吕喆 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种具有低暗电流的自驱动型光电探测器及其制备方法,属于半导体器件及其制造领域。通过确定性干法转移的方法制备的Graphene-WSe<Sub>2</Sub>-Au结构器件具有良好的光伏特性,避免了传统方法直接在二维材料上蒸镀电极容易引起的费米能级钉扎效应,器件具有良好的光响应。由于器件的两个异质结WSe<Sub>2</Sub>-Graphene结和WSe<Sub>2</Sub>-Au结具有不对称性,器件具有自驱动特性,可以在零偏压下工作,此时的暗电流几乎可以忽略；此外,由于隧穿层和俘获层的引入,使得即使器件在外部偏压下工作的时候,也能将暗电流控制在很低的数量级。(The invention discloses a self-driven photoelectric detector with low dark current and a preparation method thereof, belonging to the field of semiconductor devices and manufacturing thereof. Graphene-WSe prepared by deterministic dry transfer method 2 The Au structure device has good photovoltaic property, the Fermi level pinning effect easily caused by directly evaporating the electrode on the two-dimensional material by the traditional method is avoided, and the device has good photoresponse. Due to two heterojunctions WSe of the device 2 -Graphene junction and WSe 2 The Au junction has asymmetry, the device has self-driving characteristics, and can work under zero bias, and the dark current is almost negligible; in addition, due to the guiding of the tunneling layer and the trapping layerIn turn, dark current can be controlled to a very low order of magnitude even when the device is operated under an external bias.)

1. The self-driven photoelectric detector with low dark current is characterized by comprising a substrate, a two-dimensional semiconductor material sheet, two metal electrodes, a tunneling layer and a trapping layer, wherein the two metal electrodes are respectively deposited on two sides of the substrate, the tunneling layer is positioned on the top of the two-dimensional semiconductor heterojunction material sheet, and the trapping layer is positioned above the tunneling layer; said two-dimensional semiconductor material flakes are respectively transition metal chalcogenide WSe₂And graphene, wherein the tunneling layer is made of HfO (high-k oxide)₂The trapping layer is made of Si₃N₄。

2. A self-driven type photodetector with a low dark current according to claim 1, characterized in that: the metal electrode is formed by 50nmAu/10 nmTi.

3. A method of fabricating a self-driven photodetector having a low dark current, comprising the steps of:

s1, preparing a two-dimensional material;

s2, preparing an electrode material on the substrate;

s3, constructing a heterojunction;

s4, preparing a tunneling layer and a trapping layer on the heterojunction material;

s5 Graphene-WSe prepared₂Preparing a passivation layer on the Au device according to requirements to protect the stability of the two-dimensional material.

4. The method of manufacturing a self-driven type photodetector with a low dark current according to claim 3, wherein: in step S1, the two-dimensional material is obtained by mechanical stripping or chemical vapor deposition.

5. The method of manufacturing a self-driven type photodetector with a low dark current according to claim 3, wherein: in the step S2, Au/Ti (50nm/10nm) electrodes are obtained by electron beam evaporation and deposited on both sides of a silicon substrate with SiO 300nm₂And (4) silicon wafers with oxide layers.

6. The method of manufacturing a self-driven type photodetector with a low dark current according to claim 3, wherein: in the step S3, the obtained WSe₂The flakes and graphene flakes are transferred to the substrate by a two-step deterministic transfer process. And one side of the graphene sheet is pressed on the WSe₂On a sheet, with WSe₂The other side of the metal electrode is pressed on the gold electrode, and the metal electrode is ohmic contact; WSe₂The other side of the sheet is pressed against the metal electrode to form a schottky junction with the gold electrode. Thereby forming Graphene-WSe₂-devices of Au structure.

7. The method of claim 3, wherein in step S4, an atomic layer deposition (A L D) is first used in WSe₂Depositing a layer of HfO on top of the graphene heterojunction material₂Layer as a tunneling layer, and then preparing Si by liquid lift-off method₃N₄Dispersed liquid drop of nano-sheet in HfO₂On top and dried at room temperature for 24 hours to form a trapping layer.

8. The method of manufacturing a self-driven type photodetector with a low dark current according to claim 3, wherein: in step S5, a material of the passivation layer is typically photoresist or silicon nitride.

Technical Field

The invention relates to the field of semiconductor devices and manufacturing thereof, in particular to a self-driven photoelectric detector with low dark current and a preparation method thereof.

Background

The photoelectric detector is a detection device for converting optical signals into electric signals, and has wide and important application in military and civil fields. In military affairs, the method is mainly used for guidance, radar monitoring, optical communication and other aspects; it also has important application in the aspects of camera shooting, infrared detection, temperature measurement and the like in civil use.

Currently, silicon-based photodetectors are the mainstay behind commercial image sensors embedded in cell phones, computers and digital cameras, and in particular, PN junction-based photodiodes are becoming more and more popular in consumer electronics products due to their compatibility of fabrication processes with mainstream Complementary Metal Oxide Semiconductor (CMOS) technology. However, the silicon semiconductor has a relatively large forbidden band width, and thus it is difficult to detect the infrared band. Therefore, the discovery of some two-dimensional materials has made a significant breakthrough in the development of photodetectors. The good optical, electrical and thermal properties and the good mechanical properties of the two-dimensional material make the two-dimensional material become a good basic material for manufacturing the photoelectric detector, and the detection waveband and the detection performance of the photoelectric detector can be adjusted by changing the thickness of the two-dimensional material and constructing a heterojunction between the two-dimensional materials. Therefore, the two-dimensional material has great development potential in the field of photoelectric detection.

In order to meet the application of the photoelectric detector in the fields of biological imaging, environmental monitoring and the like, photoelectric devices based on some novel semiconductor materials and some novel structures begin to emerge, and particularly with the discovery of graphene and some two-dimensional layered materials, the research on the photoelectric detector is researched

Pushing a new wave. The almost whole spectrum required by photoelectric detection is covered from zero-band-gap graphene, transition metal chalcogenide with adjustable band gap and hexagonal boron nitride (h-BN) with the band gap width of 6 eV. With the development and innovation of some material growth and transfer methods, the integration of large-area two-dimensional material devices and silicon CMOS integrated circuits is made possible, and in addition, the absorption rate of photons by the two-dimensional material is far higher than that of silicon, which enables most of the light absorption to be realized even on very thin two-dimensional materials, which means the potential integration of a thin two-dimensional material layer with the underlying silicon CMOS processing circuits on a high-performance image sensor.

In the past decade, based on different two-dimensional materials such as Graphene, MoS₂、WSe₂Etc. have been demonstrated to have excellent performance. Based on single layer WSe₂The p-n junction photoelectric detector shows obvious photovoltaic effect, and different two-dimensional materials are combined together to form the heterojunction structure photoelectric detector with obvious photovoltaic effect due to the fact that different two-dimensional materials have different carrier polarities. Under the condition of no external bias voltage, a built-in electric field is formed due to the existence of a potential barrier in the self structure, and the property of generating photocurrent due to the drift of photogenerated carriers under the illumination condition is called self-driving, and the photoelectric detector is called a self-driving type photoelectric detector. Since the self-driven device can work without external voltage or energy supply, the self-driven device is indispensable in the application fields of outdoor environment sensing of wireless sensor networks, wearable medical monitoring and the like.

In addition, the self-driven type photodetector does not need to operate under an external bias condition, so that it has extremely low dark current.

Disclosure of Invention

The present invention is directed to solving the above problems, and provides a self-driven photodetector with low dark current and a method for manufacturing the same.

In order to achieve the purpose, the invention adopts the following technical scheme:

a self-driven photodetector with low dark current comprises a substrate, a two-dimensional semiconductor material sheet transferred on the substrate, two metal electrodes, a tunneling layer and a trapping layer, wherein the two metal electrodes are respectively deposited on two sides of the substrate, the tunneling layer is positioned on the top of the two-dimensional semiconductor material sheet, and the trapping layer is positioned above the tunneling layer; said two-dimensional semiconductor material flakes are respectively transition metal chalcogenide WSe₂And graphene, wherein the tunneling layer is made of HfO (high-k oxide)₂The trapping layer is made of Si₃N₄。

Further, the two metal electrodes were formed using 50nmAu/10 nmTi.

The other technical scheme adopted by the invention for solving the technical problem is as follows:

a method of fabricating a self-driven photodetector having a low dark current, comprising the steps of:

s1, preparing a two-dimensional material;

s2, preparing an electrode material on the substrate;

s3, constructing a heterojunction;

s4, preparing a tunneling layer and a trapping layer on the heterojunction material;

s5 Graphene-WSe prepared₂Preparing a passivation layer on the Au device according to requirements to protect the stability of the two-dimensional material.

Further, in step S1, the two-dimensional material is obtained by mechanical stripping or chemical vapor deposition.

Further, in the step S2, Au/Ti (50nm/10nm) electrodes are obtained by electron beam evaporation and deposited on both sides of the silicon substrate, which is made of SiO with a thickness of 300nm₂And (4) silicon wafers with oxide layers.

Further, in the step S3, the obtained WSe₂The flakes and graphene flakes are transferred to the substrate by a two-step deterministic transfer process. And one side of the graphene sheet is pressed on the WSe₂On a sheet, with WSe₂The other side of the metal electrode is pressed on the gold electrode, and the metal electrode is ohmic contact; WSe₂The other side of the sheet is pressed against the metal electrode to form a schottky junction with the gold electrode. Thereby forming Graphene-WSe₂-devices of Au structure.

Further, in the step S4, an atomic layer deposition technique (A L D) is firstly adopted in WSe₂Depositing a layer of HfO on top of the graphene heterojunction material₂Layer as a tunneling layer, and then preparing Si by liquid lift-off method₃N₄Dispersed liquid drop of nano-sheet in HfO₂On top and dried at room temperature for 24 hours to form a trapping layer.

8. The method for manufacturing a self-driven photodetector with low dark current according to claim 4, wherein: in step S5, a material of the passivation layer is typically photoresist or silicon nitride.

Compared with the prior art, the invention provides the self-driven photoelectric detector with low dark current and the preparation method thereof, and the self-driven photoelectric detector has the following beneficial effects:

1. the invention has the beneficial effects that: Graphene-WSe prepared by deterministic dry transfer method₂The Au structure has good photovoltaic property, the Fermi level pinning effect easily caused by directly evaporating the electrode on the two-dimensional material by the traditional method is avoided, and the device has good photoresponse.

2. The invention has the following beneficial effects: due to two heterojunctions WSe of the device₂-Graphene junction and WSe₂The Au junction has asymmetry, the device has self-driving characteristics, and can work under zero bias, and the dark current is almost negligible; in addition, due to the introduction of the tunneling layer and the trapping layer, the dark current can be controlled to be a very low order of magnitude even when the device is operated under an external bias.

Drawings

Fig. 1 is a front view of an embodiment of a self-driven type photodetector with low dark current according to the present invention;

fig. 2 is a perspective view of an embodiment of a self-driven photodetector with low dark current according to the present invention;

FIG. 3 is a perspective view of a two-dimensional semiconductor material heterojunction for one embodiment of a self-driven photodetector with low dark current in accordance with the present invention;

fig. 4 is a schematic flow chart of a method for manufacturing a self-driven photodetector with low dark current according to an embodiment of the present invention.

Fig. 5 is an output curve of a self-driven type photodetector with low dark current according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.