CN106784115A - Adjustable PIN structural graphene optical detector of fermi level and preparation method thereof - Google Patents

Abstract

The present invention relates to graphene optical detector field, device of the present invention is followed successively by substrate, metal level, insulating barrier, P doped graphenes layer, dielectric layer and N doped graphenes layer from top to bottom, and grid voltage is added in metal level；There is source electrode, drain electrode, first electrode, wherein source electrode and drain electrode are respectively positioned at the both sides of the first graphene layer, and are connected with the first graphene layer on insulating barrier；First electrode and second electrode are connected positioned at the both sides of the second graphene layer, and first electrode with the second graphene layer respectively；P doped graphenes layer, dielectric layer and N doped graphenes layer constitute PIN structural；First graphene layer, source electrode, drain electrode, insulating barrier and metal level constitute a field-effect transistor.The present invention makes the detector that field-effect transistor structure is mutually combined with PIN structural using grapheme material, realizes ultraviolet to the response quickly detection high of infrared broadband.

Description

PIN structure graphene photodetector with tunable Fermi level and its preparation method

technical field

The invention relates to the field of graphene photodetectors, in particular to a PIN-structure graphene photodetector with adjustable Fermi energy level and a preparation method thereof.

Background technique

Graphene (Grahpene) is a new carbonaceous material that is tightly packed into a two-dimensional honeycomb lattice structure by a single layer of carbon atoms. It has excellent mechanical, electrical, thermal and optical properties. Since 2004, the team of Novoselov and Geim Since single-layer graphene at room temperature was prepared by mechanical exfoliation, it has gradually become a research hotspot. Graphene is undoubtedly the thinnest known material, with a single layer of graphene only 0.3 nanometers thick (one carbon atom thick), but it is also the hardest nanomaterial. Graphene can absorb 2.3 percent of white light, much higher than other allotropes of carbon. Graphene can observe the Hall effect at room temperature. Graphene is a semi-metallic zero-bandgap material, which makes it possible to adjust the conductivity of graphene by controlling the gate, and it can make it impossible to turn off below a certain limit, and open several kinds of forbidden bands Methods have been proposed and demonstrated.

Graphene photodetectors are roughly divided into metal graphene contact photodetectors, plasmon resonance photodetectors, quantum dot graphene hybrid photodetectors, graphene heterojunction photodetectors, and so on. In 2009, Fengnian Xia, Thomas Mueller and others used mechanically exfoliated graphene to make a metal graphene contact photodetector, which was also the first graphene photodetector, and its appearance attracted widespread attention. The disadvantage is that the light response is only 0.5mA/W. In 2010, Echtermeyer studied the influence of different nanostructures on the photoelectric response, and found that changing the size of the nanostructures can adjust the light absorption of different wavelengths, thus preparing a plasmon resonance photodetector based on graphene, but unfortunately its photoresponse rate is not high. In 2012, Gerasimos Konstantatos proposed mixing quantum dots and graphene to prepare a quantum dot-graphene hybrid photodetector. This device has high responsivity, but has shortcomings such as too large dark current, slow response speed, and low response rate. .

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, to provide a PIN structure graphene photodetector with adjustable Fermi energy level and its preparation method, the PIN structure graphene photodetector with adjustable Fermi energy level and The preparation method can solve the problems of low light absorption rate and slow response speed of graphene as a photodetector material.

In order to meet the above-mentioned requirements, the technical solution adopted by the present invention is: provide a PIN structure graphene photodetector with adjustable Fermi level, which is followed by substrate, metal layer, insulating layer, first graphene photodetector from bottom to top. layer, dielectric layer and second graphene layer; the insulating layer has a source electrode, a drain electrode and a first electrode, wherein the source electrode and the drain electrode are all connected to the first graphene layer, and the first electrode is connected to the second graphene layer. Two graphene layers are connected; any one of the first graphene layer and the second graphene layer is P-doped, and the other is N-doped, and the first graphene layer, the dielectric layer and the second graphene layer constitute a PIN Structure; the first graphene layer, the source electrode, the drain electrode, the insulating layer and the metal layer form a field effect transistor.

A method for preparing a PIN structure graphene photodetector with adjustable Fermi level is provided, comprising the following steps:

S1, depositing a metal layer on the surface of the substrate;

S2, growing an insulating layer on the surface of the metal layer;

S3. Depositing a metal electrode layer on the surface of the insulating layer, and photoetching the metal electrode layer to form a source electrode, a drain electrode, a first electrode and a second electrode;

S4, transferring a layer of graphene to the surface of the insulating layer to form a first graphene layer, the first graphene layer is respectively connected to the source electrode and the drain electrode, and the first graphene layer is doped;

S5, growing a dielectric layer on the surface of the first graphene layer;

S6. Transferring a layer of graphene to the surface of the dielectric layer to form a second graphene layer, the second graphene layer is connected to the first electrode, and doping the second graphene layer;

S7. Etching away excess graphene on the surface of the device to complete the preparation of the device

The PIN structure graphene photodetector with adjustable Fermi level and the preparation method thereof have the following advantages:

(1) On the basis of graphene heterojunction, a dielectric layer is added between P-doped graphene and N-doped graphene as I layer to form a PIN structure, which can effectively reduce the dark current of the device and improve the performance of the device. The signal-to-noise ratio improves the responsivity and response speed of the device as a graphene photodetector;

(2) The metal layer and the insulating layer form a resonant cavity, so that the light is continuously reflected in the cavity, so as to improve the light responsivity, and the difference in the height of the resonant cavity corresponds to different absorption wavelengths;

(3) The first graphene layer, the source electrode, the drain electrode, the insulating layer and the metal layer constitute a field effect transistor, and the Fermi level of the first graphene layer can be adjusted by applying a gate voltage to the metal layer, Thus, the changing Fermi level difference between the first graphene layer and the second graphene layer is obtained, which effectively enhances the responsivity to different detection bands.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the application and constitute a part of the application. In these drawings, the same reference numerals are used to indicate the same or similar parts. The illustrative embodiments of the application and their descriptions are used The purpose of explaining this application does not constitute an improper limitation of this application. In the attached picture:

Fig. 1 is a schematic cross-sectional view of the device of the present application;

Fig. 2 is the schematic plan view of the device of the present application;

Fig. 3 is a schematic flow chart of the method of the present application;

Fig. 4 is a diagram of the current change of the device tested with the SCS4200 semiconductor tester under the light change of 632nm.

detailed description

In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

For simplicity, some technical features known to those skilled in the art are omitted from the following description.

According to one embodiment of the present application, a PIN structure graphene photodetector with adjustable Fermi level is provided, as shown in Figures 1 and 2, substrate 1, metal layer 2, insulating layer from bottom to top 3. The first graphene layer 5, the dielectric layer 6 and the second graphene layer 7, when in use, apply a gate voltage to the metal layer 2; the insulating layer 3 has a source electrode 4a, a drain electrode 4b and a first electrode 4c, in general, the production of four electrodes can be completed at one time, and the second electrode 4d other than the source electrode 4a, the drain electrode 4b and the first electrode 4c is used as a spare electrode; wherein the source electrode 4a and the drain electrode 4b Respectively located on both sides of the first graphene layer 5, and all connected with the first graphene layer 5; the first electrode 4c and the second electrode 4d are respectively located on both sides of the second graphene layer 7, and the first electrode 4c Connected with the second graphene layer 7; wherein the first graphene layer 5 is P-doped, the second graphene layer 7 is N-doped, the first graphene layer 5, the dielectric layer 6 and the second graphene layer 7 A PIN structure is formed; the first graphene layer 5, the source electrode 4a, the drain electrode 4b, the insulating layer 3 and the metal layer 2 form a field effect transistor.

Further, the metal layer 2 is Cu, Au, Al, Ni, NiCr or Ag, and the thickness of the metal layer 2 is 100-1000 nm.

Further, the insulating layer 3 is SiO ₂ , Si ₃ N ₄ , MnO ₂ or MgO, and the thickness of the insulating layer 3 is 100-1000 nm.

Further, the dielectric layer 6 is Si ₃ N ₄ , MgO, SiO ₂ or undoped graphene, and the thickness of the dielectric layer 6 is 1-500 nm.

A preparation method of a PIN structure graphene photodetector with adjustable Fermi level, as shown in Figure 3, comprises the following steps:

S1, cleaning the highly doped silicon substrate 1 and blowing it dry, depositing a 300nm thick Cu thin film on the surface of the silicon substrate 1 as the gate of the field effect transistor and the metal layer 2 of the entire device;

S2, with the metal layer 2 as the base, grow a layer of 300nm thick SiO ₂ as the insulating layer 3 of the field effect transistor with the method of PECVD;

S3, depositing a metal electrode layer on the surface of the insulating layer 3, and photoetching the metal electrode layer to form a source electrode 4a, a drain electrode 4b, a first electrode 4c, and a second electrode 4d;

S4, transfer one layer of graphene to the surface of the insulating layer to form the first graphene layer 5, the first graphene layer 5 is connected with the source electrode 4a and the drain electrode 4b respectively, and the method for spin-coating Au and toluene mixed solution P-type doping is performed on the first graphene layer 5;

S5, growing a dielectric layer 6 on the surface of the first graphene layer 5;

S6, transfer one layer of graphene to the surface of the medium layer to form the second graphene layer 7, the second graphene layer 7 is connected to the first electrode 4c, and adopt the method of drip coating hydrazine solution or spin coating PEI solution to the second The graphene layer 7 is N-type doped;

S7. Etching off excess graphene on the surface of the device to complete the preparation of the device.

A 632nm laser was used as the light source for detector performance testing. Set the gate voltage to -1V, the voltage between the source and the drain (ground) to 0.5V, use the S[1] semiconductor tester to test the electrical output signal between the drain electrode 4b and the first electrode 4c, and the test results As shown in Figure 4. It can be seen that the structure of the detector has a significant electrical response signal output under the irradiation of a 632nm light source after chopping, the response current is about 10μA, and the response speed is lower than 1ms. The response current of the device and the The optimized band for the response. Therefore, the performance of high responsivity and high response speed is obtained through the composite detector structure of the field effect transistor and the PIN structure of the present invention.

The above-mentioned embodiments only represent several implementations of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the claims.

"SCS4200" is recorded in the original submission, please confirm.

Claims (10)

1. the adjustable PIN structural graphene optical detector of a kind of fermi level, it is characterised in that be followed successively by from top to bottom substrate, Metal level, insulating barrier, the first graphene layer, dielectric layer and the second graphene layer；There is source electrode, drain electrode on insulating barrier And first electrode, wherein source electrode and drain electrode be connected with the first graphene layer, first electrode and the second Graphene Layer is connected；Any one is P doping in wherein the first graphene layer and the second graphene layer, and another is that N adulterates, the first stone Black alkene layer, dielectric layer and the second graphene layer constitute PIN structural；First graphene layer, source electrode, drain electrode, insulating barrier And metal level constitutes a field-effect transistor.

2. the adjustable PIN structural graphene optical detector of fermi level according to claim 1, it is characterised in that described Metal level is Cu, Au, Al, Ni, NiCr or Ag, and the thickness of metal level is 100-1000 nm.

3. the adjustable PIN structural graphene optical detector of fermi level according to claim 1, it is characterised in that described Insulating barrier is SiO₂、Si₃N₄、MnO₂Or MgO, the thickness of insulating barrier is 100-1000 nm.

4. the adjustable PIN structural graphene optical detector of fermi level according to claim 1, it is characterised in that described Dielectric layer is Si₃N₄ 、MgO、SiO₂Or the Graphene of undoped p.

5. the adjustable PIN structural graphene optical detector of fermi level according to claim 1 or 4, it is characterised in that institute The thickness for stating dielectric layer is 1-500 nm.

6. the adjustable PIN structural graphene optical detector of fermi level according to claim 1, it is characterised in that described Also have as standby second electrode on insulating barrier.

7. the preparation method of the adjustable PIN structural graphene optical detector of a kind of fermi level, it is characterised in that including following step Suddenly：

S1, substrate surface deposited metal layer；

S2, layer on surface of metal grow insulating barrier；

S3, layer of metal electrode layer is deposited in surface of insulating layer, photolithographic electrode layer forms source electrode, drain electrode, the One electrode and second electrode；

S4, transfer one layer graphene to surface of insulating layer formed the first graphene layer, the first graphene layer respectively with source electrode It is connected with drain electrode, and the first graphene layer is doped；

S5, in the first graphene layer superficial growth dielectric layer；

S6, one layer graphene of transfer to dielectric layer surface form the second graphene layer, and the second graphene layer is connected with first electrode Connect, and the second graphene layer is doped；

S7, the unnecessary Graphene of device surface is etched away, complete the preparation of device.

8. the preparation method of the adjustable PIN structural graphene optical detector of fermi level according to claim 7, its feature It is that p-type doping is carried out to the first graphene layer in the step S4, n-type doping is carried out to the second graphene layer in step S6； Or n-type doping is carried out to the first graphene layer in step S4, p-type doping is carried out to the second graphene layer in step S6.

9. the preparation method of the adjustable PIN structural graphene optical detector of fermi level according to claim 8, its feature It is that the p-type doping is doped using the method for spin coating Au and toluene mixed solution to graphene layer.

10. the preparation method of the adjustable PIN structural graphene optical detector of fermi level according to claim 8, it is special Levy and be, the n-type doping is doped using the method for drop coating hydrazine solution or spin coating PEI solution to graphene layer.