Novel dual-band avalanche photodetector and preparation method thereof

Abstract

The invention relates to a novel dual-band avalanche photodetector and a preparation method thereof, and the device comprises a SiO2 dielectric layer which is provided with a through groove; the drain electrode layer is located on a part of the surface of one side of the SiO2 dielectric layer; the two-dimensional material layer extends to the surface of the SiO2 dielectric layer and the through groove from the surface of the drain electrode layer and forms a step shape, the drain electrode layer and the two-dimensional material layer form a Schottky junction, and the Schottky junction can generate an avalanche breakdown phenomenon under negative bias voltage; the three-dimensional material layer is located on the side, away from the drain electrode layer, of the SiO2 dielectric layer so that the three-dimensional material layer and the two-dimensional material layer can form a PN junction, the PN junction can generate an avalanche breakdown phenomenon under positive bias voltage, and visible-infrared dual-band photoelectric detection can be achieved through combination of the Schottky junction and the PN junction. And the source electrode layer is positioned on one side, far away from the SiO2 dielectric layer, of the three-dimensional material layer. The device can give consideration to visible-infrared dual-band photoelectric detection and avalanche characteristics at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of avalanche photodetection, and particularly relates to a novel dual-band avalanche photodetector and a preparation method thereof. Background Art

[0002] An avalanche photodiode (APD) is a highly sensitive photodetector that can convert an incident optical signal into an electrical signal and significantly amplify a weak photocurrent through a built-in gain mechanism (avalanche breakdown effect). Here, the avalanche breakdown effect can be understood as follows: when the electric field in a semiconductor exceeds a certain specific value, some carriers can obtain sufficient high energy from the electric field and, through mutual collisions, the high-energy carriers transfer part of their energy to the electrons in the valence band, exciting them to the conduction band, thereby generating a large number of electron-hole pairs. This process is called impact ionization. The generated electrons and holes also obtain energy from the electric field and continuously generate a large number of new electron-hole pairs during their movement. This will cause a large multiplication of carriers, just like an avalanche; during this process, the current increases rapidly, resulting in device breakdown.

[0003] Avalanche photodiodes are commonly used in fields such as optical communication, laser ranging, medical imaging, and quantum optics, for example, visible-infrared dual-band photodetection. However, currently, the photodetectors on the market that can achieve visible-infrared dual-band photodetection do not have avalanche characteristics, and those with avalanche characteristics cannot achieve visible-infrared dual-band photodetection. In short, currently, the structures of avalanche photodetectors on the market are complex and cannot simultaneously take into account visible-infrared dual-band photodetection and avalanche characteristics. Summary of the Invention

[0004] To solve the above problems existing in the prior art, the present invention provides a novel dual-band avalanche photodetector and a preparation method thereof. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0005] In a first aspect, the present invention provides a novel dual-band avalanche photodetector, including:

[0006] SiO 2 dielectric layer, a through groove is formed on the SiO 2 dielectric layer, and the depth of the through groove is equal to the thickness of the SiO 2 dielectric layer; a drain electrode layer, located on a partial surface on one side of the SiO 2 dielectric layer; a two-dimensional material layer, extending from the surface of the drain electrode layer to the surface of the SiO 2 dielectric layer and into the through groove and forming a stepped shape; and, a Schottky junction is formed between the drain electrode layer and the two-dimensional material layer; a three-dimensional bulk material layer, located on the SiO 2The surface of the dielectric layer away from the drain electrode layer forms a PN junction with the two-dimensional material layer; the source electrode layer is located on the surface of the three-dimensional bulk material layer away from the SiO 2 surface of the dielectric layer.

[0007] In some embodiments, the material of the two-dimensional material layer includes WS 2 , and the thickness is 30 nm to 50 nm.

[0008] In some embodiments, the length of the through groove is greater than or equal to 50 μm.

[0009] In some embodiments, the material of the three-dimensional bulk material layer is P-type doped Ge, the thickness is 140 μm to 160 μm, and the resistivity is 0.005 Ω.

[0010] In some embodiments, the thickness of the SiO 2 dielectric layer is 80 nm to 120 nm.

[0011] In some embodiments, the materials of the drain electrode layer and the source electrode layer are both stacked Ni metal and Au metal, wherein the thickness of the Ni metal is 3 nm to 8 nm, and the thickness of the Au metal is 80 nm to 120 nm.

[0012] In some embodiments, a graphene layer is provided on a partial surface of the drain electrode layer and a partial surface of the two-dimensional material layer, and the graphene layer is stepped.

[0013] In some embodiments, the thickness of the graphene layer is greater than or equal to 20 nm.

[0014] In a second aspect, the present invention provides a method for manufacturing a novel dual-band avalanche photodetector, and the manufacturing method is used to manufacture the novel dual-band avalanche photodetector described in the first aspect above. The manufacturing method includes:

[0015] Using plasma-enhanced chemical vapor deposition process to prepare a SiO 2 dielectric layer, and etching a through groove on the SiO 2 dielectric layer; using electron beam evaporation deposition process to deposit a drain electrode layer on a partial surface of one side of the SiO 2 dielectric layer; using a mechanical transfer method to prepare a two-dimensional material layer on the surface of the drain electrode layer extending to the surface of the SiO 2 dielectric layer and in the through groove, and the two-dimensional material layer is stepped; preparing a three-dimensional bulk material layer on the surface of the SiO 2 dielectric layer away from the drain electrode layer; preparing a source electrode layer on the surface of the three-dimensional bulk material layer away from the SiO 2 dielectric layer.

[0016] In some embodiments, the preparation method further includes: preparing a graphene layer on the surface of the two-dimensional material layer extending to the surface of the drain electrode layer.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] Aiming at the problems that the structure of avalanche photodetectors on the current market is complex and it is impossible to simultaneously take into account the photoelectric detection and avalanche characteristics of the visible-infrared dual band, the present invention provides a novel dual-band avalanche photodetector and its preparation method. The device forms a Schottky junction that can undergo avalanche breakdown under negative bias by using a drain electrode layer and a two-dimensional material layer, and forms a PN junction that can undergo avalanche breakdown under positive bias by using a two-dimensional material layer and a three-dimensional bulk material layer, so that the device can have avalanche characteristics whether it is in a positive bias or negative bias state; moreover, the "back-to-back" structure composed of the Schottky junction and the PN junction can respond to visible light incidence and respond to infrared light incidence under positive bias. By changing the bias state of the device during use, different bands can be responded to, and it has visible-infrared dual-band avalanche photoelectric detection performance with adjustable bias, thus simultaneously taking into account the photoelectric detection and avalanche characteristics of the visible-infrared dual band, and having the advantages of simple structure, easy preparation and high integration. Description of the Drawings

[0019] Figure 1 is a schematic plan view of a novel dual-band avalanche photodetector provided by an embodiment of the present invention;

[0020] Figure 2 is an equivalent circuit diagram of the novel dual-band avalanche photodetector provided by an embodiment of the present invention;

[0021] Figure 3 is a light response diagram of the novel dual-band avalanche photodetector under visible-infrared dual bands provided by an embodiment of the present invention;

[0022] Figure 4 is another schematic plan view of a novel dual-band avalanche photodetector provided by an embodiment of the present invention;

[0023] Figure 5 is for Figure 4 an example diagram of simulating the device shown;

[0024] Figure 6 is a flowchart of a preparation method of a novel dual-band avalanche photodetector provided by an embodiment of the present invention.

[0025] Reference Signs:

[0026] 1: SiO 21: dielectric layer; 2: drain electrode layer; 3: two-dimensional material layer; 4: three-dimensional bulk material layer; 5: source electrode layer; 6: graphene layer. Detailed implementation manners

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0028] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0029] A novel dual-band avalanche photodetector and its preparation method proposed by the present invention will be described in detail below with reference to embodiments. It should be noted that the novel dual-band avalanche photodetector provided by the present invention includes two structures, which will be described one by one below with reference to the accompanying drawings.

[0030] Embodiment 1

[0031] Figure 1 is a schematic plan view of a novel dual-band avalanche photodetector provided by an embodiment of the present invention. As Figure 1 shown, the device includes: SiO 2 dielectric layer 1, a through groove is formed in the SiO 2 dielectric layer 1, and the depth of the through groove is equal to the thickness of the SiO 2 dielectric layer 1; a drain electrode layer 2, located on a part of the surface on one side of the SiO 2 dielectric layer 1 to form a Schottky junction with the two-dimensional material layer 3, and the Schottky junction can undergo avalanche breakdown under a negative bias voltage; a two-dimensional material layer 3, extending from the surface of the drain electrode layer 2 to the surface of the SiO 2 dielectric layer 1 and into the through groove and forming a stepped shape; a three-dimensional bulk material layer 4, located on the surface of the SiO 2 dielectric layer 1 away from the drain electrode layer 2 to form a PN junction with the two-dimensional material layer 3, and the PN junction can undergo avalanche breakdown under a positive bias voltage. Moreover, the Schottky junction and the PN junction form a "back-to-back" structure, and the "back-to-back" structure can respond to visible light incidence and respond to infrared light incidence under a positive bias voltage, so as to realize visible-infrared dual-band photoelectric detection; a source electrode layer 5, located on the surface of the three-dimensional bulk material layer 4 away from the SiO 2 dielectric layer 1.

[0032] Here, SiO 2 The shape of the dielectric layer 1 is a rectangular block, and SiO 2 The thickness of the dielectric layer 1 is 80 nm to 120 nm, preferably 100 nm. Among them, in SiO 2 The length of the through groove formed in the dielectric layer 1 is greater than or equal to 50 μm. It should be noted that in the present invention, the width and length of SiO 2 The dielectric layer 1 can be set according to actual needs. In a possible implementation manner, SiO 2 The width of the dielectric layer 1 is 200 μm.

[0033] Here, the materials of the drain electrode layer 2 and the source electrode layer 5 are both stacked Ni metal and Au metal. Among them, the thickness of the Ni metal is 3 nm to 8 nm, preferably 5 nm, and the thickness of the Au metal is 80 nm to 120 nm, preferably 100 nm. In a possible implementation manner, the length range of the drain electrode layer 2 is 150 μm to 200 μm, preferably 175 μm.

[0034] Here, the material of the two-dimensional material layer 3 includes WS 2 , with a thickness of 30 nm to 50 nm, and the concentration value is 1×10 18 cm -3 . The material of the three-dimensional bulk material layer 4 includes P-type doped Ge, with a thickness of 140 μm to 160 μm, a resistivity of 0.005 Ω, and the concentration value is 6×10 15 cm -3 . In the two-dimensional van der Waals contact material, WS 2 has the value of being used to develop optoelectronic devices due to its high carrier mobility, good light absorption characteristics and stability in an air environment, and the Ge material has a suitable band gap and a large absorption coefficient. Therefore, the heterojunction formed by WS 2 and Ge can broaden the light response range of the device to the communication band of 1550 nm.

[0035] In a possible implementation manner, the Au metal on the drain electrode layer 2 and SiO 2 The dielectric layer 1 forms a Schottky junction, and the two-dimensional material layer 3 and the three-dimensional bulk material layer 4 form a PN junction. The Schottky junction and the PN junction form a "back-to-back" structure. The diode with the "back-to-back" structure has the advantages of simple preparation process and easy matching with the readout circuit.

[0036] Figure 2 is the equivalent circuit diagram of the novel dual-band avalanche photodetector provided by the embodiment of the present invention. As Figure 2As shown, the Schottky junction is equivalent to inverter 1, and the PN junction is equivalent to inverter 2. The output terminal of inverter 1 is connected to the output terminal of inverter 2. The positive electrode of the source-drain voltage Vds is connected to the input terminal of inverter 1, and the negative electrode of voltage Vds is connected to the input terminal of inverter 2. In the case of a forward bias (source-drain voltage Vds > 0), the PN junction is reverse-biased while the Schottky junction is forward-biased. Avalanche breakdown occurs in the PN junction, and at the same time, light absorption occurs in the PN junction region. In the case of a reverse bias (source-drain voltage Vds < 0), the PN junction is forward-biased while the Schottky junction is reverse-biased. Avalanche breakdown occurs in the Schottky junction, and light absorption occurs in the Schottky junction region. That is to say, regardless of the bias state of the source-drain voltage Vds, the device can generate avalanche breakdown. Exemplarily, when the source-drain voltage Vds > 0, the forward avalanche voltage of the device is 10V; when the source-drain voltage Vds < 0, the negative avalanche voltage of the device is -24.5V.

[0037] In addition, since both the two-dimensional material layer 3 and the three-dimensional bulk material layer 4 can achieve light absorption, the device responds under visible light irradiation regardless of the bias state of the source-drain voltage Vds. For incident light in the infrared band, only the three-dimensional bulk material layer 4 can absorb it, so there is a light response only when Vds > 0. To verify the light absorption performance of the device, Figure 3 is the light response diagram of the novel dual-band avalanche photodetector under visible-infrared dual bands provided by the embodiment of the present invention. As Figure 3 (a) in shows that when visible light with a wavelength of 532nm is incident, the device has a light response regardless of the bias state of the source-drain voltage Vds; as Figure 3 (b) in shows that when infrared light with a wavelength of 1550nm is incident, the device has a light response only when Vds > 0. It can be seen that based on the light absorption characteristics of the two-dimensional material layer 3 and the three-dimensional bulk material layer 4, visible-infrared dual-band photoelectric detection can be achieved. In addition, during actual use, the light absorption band of the device can be changed by adjusting the bias voltage state of the device, realizing the bias-voltage adjustable visible-infrared dual-band avalanche photoelectric detection performance.

[0038] Embodiment 2

[0039] Figure 4 is another schematic plan view of a novel dual-band avalanche photodetector provided by the embodiment of the present invention. It should be noted that Figure 4 except for the added part, the other structures, components and concentrations are the same as those in Figure 1 . For the sake of brevity, they will not be described in detail here.

[0040] As Figure 4As shown, in a possible implementation, it further includes a graphene layer 6. The graphene layer 6 extends from the surface of the two-dimensional material layer 3 to the surface of the drain electrode layer 2 and forms a stepped shape. Among them, the thickness of the graphene layer 6 is greater than or equal to 20 nm.

[0041] It should be noted that the sum of the length of the graphene layer 6 on the drain electrode layer 2 and the length of the two-dimensional material layer 3 on the drain electrode layer 2 is the total length of the drain electrode layer 2. And the graphene layer 6 on the two-dimensional material layer 3 does not completely cover the two-dimensional material layer 3.

[0042] By providing the graphene layer 6 on a part of the surface of the drain electrode layer 2 and a part of the surface of the two-dimensional material layer 3, when the source-drain voltage Vds > 0, the PN junction is reverse-biased and the Schottky junction is forward-biased. At this time, the forward-biased Schottky junction region still has a certain barrier height and can divide part of the voltage. By reducing the Schottky barrier of the Schottky junction, by reducing the Schottky barrier height, the voltage division in the Schottky junction region can be reduced, thereby reducing the avalanche voltage of the PN junction. And when the source-drain voltage Vds < 0, the PN junction is forward-biased and the Schottky junction is reverse-biased. The barrier height of the forward-biased PN junction region is very low and hardly divides the voltage. So even if the Schottky barrier is reduced, the voltage division in the Schottky junction region will not change much, so the avalanche voltage hardly changes. In short, setting the graphene layer 6 can reduce the avalanche voltage of the PN junction while maintaining the original Schottky junction avalanche voltage.

[0043] To verify the effect of the additionally added graphene layer 6, Figure 5 is an example diagram of the simulation of the device provided by the embodiment of the present invention for Figure 4 shown. As Figure 5 shown, the forward avalanche voltage of the device is reduced from 10 V to 4.5 V. When the source-drain voltage Vds < 0, the PN junction is forward-biased and the Schottky junction is reverse-biased. The barrier height of the forward-biased PN junction region is very low and hardly divides the voltage. So even if the Schottky barrier is reduced, in the case of Vds < 0, the voltage division in the Schottky junction region will not change much, so the avalanche voltage hardly changes and still remains at 24.5 V as Figure 5 shown. Therefore, the device with the added graphene layer can reduce the avalanche voltage of the PN junction while maintaining the original Schottky junction avalanche voltage.

[0044] Corresponding to a novel dual-band avalanche photodetector provided by an embodiment of the present invention, the embodiment of the present invention also provides a preparation method for the novel dual-band avalanche photodetector. This preparation method is used to prepare the novel dual-band avalanche photodetector provided by the embodiment of the present invention. Figure 6It is a flowchart of a preparation method for a novel dual-band avalanche photodetector provided by an embodiment of the present invention. It should be noted that the preparation processes mentioned in the present invention are all existing preparation processes, and the sizes and materials of the foregoing layers are not elaborated here for the sake of brevity. As Figure 6 shown, the preparation method includes:

[0045] Step 110: Prepare a SiO 2 dielectric layer 1 by plasma-enhanced chemical vapor deposition process, and etch a through groove on the SiO 2 dielectric layer 1.

[0046] Exemplarily, by using the plasma-enhanced chemical vapor deposition process, deposit a 100-nm SiO 2 dielectric layer 1 in the chamber. Remove part of the SiO2 through photolithography process and reactive ion etching (RIE) to obtain a through groove, which can be used as a window to enable the subsequent prepared two-dimensional material layer 3 and three-dimensional bulk material layer 4 to contact.

[0047] Step 120: Deposit a drain electrode layer 2 on a partial surface on one side of the SiO 2 dielectric layer 1 by electron beam evaporation deposition process.

[0048] Step 130: Use the method of mechanical transfer to prepare a two-dimensional material layer 3 on the surface of the drain electrode layer 2 extending to the surface of the SiO 2 dielectric layer 1 and in the through groove, and the two-dimensional material layer 3 is in a stepped shape.

[0049] It should be noted that the two-dimensional material layer 3 located on the drain electrode layer 2 does not completely cover the drain electrode layer 2, and the two-dimensional material layer 3 located in the through groove is in a completely filled state. In addition, the thicknesses of the two-dimensional material layers 3 located on different layers are the same. Exemplarily, if the depth of the through groove is 100 nm, then the thickness of the two-dimensional material layer 3 located on the drain electrode layer 2 and the thickness of the two-dimensional material layer 3 located on the SiO 2 dielectric layer 1 are both 100 nm.

[0050] Step 140: Prepare a three-dimensional bulk material layer 4 on the surface of the SiO 2 dielectric layer 1 away from the drain electrode layer 2.

[0051] Step 150: Prepare a source electrode layer 5 on the surface of the three-dimensional bulk material layer 4 away from the SiO 2 dielectric layer 1.

[0052] After completing steps 110-150, the novel dual-band avalanche photodetector in Figure 1 can be prepared. To obtain Figure 4In the novel dual-band avalanche photodetector, the manufacturing method provided by the embodiments of the present invention further includes: preparing a graphene layer 6 on the surface of the two-dimensional material layer 3 and extending to the surface of the drain electrode layer 2.

[0053] Aiming at the problems that the avalanche photodetectors on the current market have complex structures and cannot simultaneously take into account the photoelectric detection and avalanche characteristics of the visible-infrared dual-band, the present invention provides a novel dual-band avalanche photodetector and its manufacturing method. By using the drain electrode layer and the SiO 2 dielectric layer to form a Schottky junction that can undergo avalanche breakdown under negative bias, and using the two-dimensional material layer and the three-dimensional bulk material layer to form a PN junction that can undergo avalanche breakdown under positive bias, the device can have avalanche characteristics whether it is in a positive bias or negative bias state; moreover, the Schottky junction and the PN junction can respond to visible light incidence and respond to infrared light incidence under positive bias. By changing the bias state of the device during use, different bands can be responded to, and it has the infrared-visible dual-band avalanche photoelectric detection performance with adjustable bias, thus simultaneously taking into account the photoelectric detection of the infrared light-visible light dual-band and the avalanche characteristics, and having the advantages of simple structure, easy preparation and high integration.

[0054] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A novel dual-band avalanche photodetector, characterized in that: include: A SiO2 dielectric layer (1), wherein a through groove is formed on the SiO2 dielectric layer (1), and the depth of the through groove is equal to the thickness of the SiO2 dielectric layer (1); A drain electrode layer (2), located on a portion of the surface of one side of the SiO2 dielectric layer (1); a two-dimensional material layer (3) extending from the surface of the drain electrode layer (2) to the surface of the SiO2 dielectric layer (1) and into the through groove and forming a step shape; and the drain electrode layer (2) and the two-dimensional material layer (3) form a Schottky junction; A three-dimensional material layer (4) is located on a surface of the SiO2 dielectric layer (1) away from the drain electrode layer (2) to form a PN junction with the two-dimensional material layer (3); The source electrode layer (5) is located on a surface of the three-dimensional material layer (4) away from the SiO2 dielectric layer (1).

2. The novel dual-band avalanche photodetector according to claim 1, characterized in that: The material of the two-dimensional material layer (3) includes WS2, and the thickness is 30nm-50nm.

3. The novel dual-band avalanche photodetector according to claim 1, characterized in that: The length of the through groove is greater than or equal to 50 μm.

4. The novel dual-band avalanche photodetector according to claim 1, characterized in that: The material of the three-dimensional material layer (4) is P-type doped Ge, with a thickness of 140 μm to 160 μm and a resistivity of 0.005 Ω.

5. The novel dual-band avalanche photodetector according to claim 1, characterized in that: The thickness of the SiO2 dielectric layer (1) is 80nm-120nm.

6. The novel dual-band avalanche photodetector according to claim 1, characterized in that: The materials of the drain electrode layer (2) and the source electrode layer (5) are both stacked Ni metal and Au metal, wherein the thickness of the Ni metal is 3nm to 8nm, and the thickness of the Au metal is 80nm to 120nm.

7. The novel dual-band avalanche photodetector according to claim 1, characterized in that: It also includes a graphene layer (6), wherein the graphene layer (6) extends from the surface of the two-dimensional material layer (3) to the surface of the drain electrode layer (2) and forms a step shape.

8. The novel dual-band avalanche photodetector according to claim 7, characterized in that: The thickness of the graphene layer (6) is greater than or equal to 20 nm.

9. A method for preparing a novel dual-band avalanche photodetector, characterized in that: The preparation method is used to prepare the novel dual-band avalanche photodetector according to any one of claims 1 to 8, and the preparation method comprises: Using a plasma enhanced chemical vapor deposition process to prepare a SiO2 dielectric layer (1), and etching a through groove on the SiO2 dielectric layer (1); Depositing a drain electrode layer (2) on a portion of the surface of one side of the SiO2 dielectric layer (1) by using an electron beam evaporation deposition process; By means of mechanical transfer, a two-dimensional material layer (3) is prepared on the surface of the drain electrode layer (2) extending to the surface of the SiO2 dielectric layer (1) and in the through groove, wherein the two-dimensional material layer (3) is in a step shape; Preparing a three-dimensional material layer (4) on a surface of the SiO2 dielectric layer (1) away from the drain electrode layer (2); A source electrode layer (5) is prepared on a surface of the three-dimensional material layer (4) that is away from the SiO2 dielectric layer (1).

10. The method for preparing the novel dual-band avalanche photodetector according to claim 9, characterized in that: The preparation method further comprises: A graphene layer (6) is prepared on the surface of the two-dimensional material layer (3) extending to the surface of the drain electrode layer (2).

Images