Polarization-dependent bipolar infrared detector based on corner heterojunction, preparation method and photocurrent response polarity regulation and control method

Abstract

The invention discloses a polarization-dependent bipolar infrared detector based on a corner heterojunction, a preparation method and a photocurrent response polarity regulation and control method. The polarization-dependent bipolar infrared detector comprises a substrate, a corner Van der Waals heterojunction and a transferable metal electrode, wherein the corner Van der Waals heterojunction and the transferable metal electrode are sequentially stacked on the substrate from bottom to top; the corner Van der Waals heterojunction is obtained by sequentially stacking p-type semiconductors, n-type semiconductors and p-type semiconductors to form an npn junction and forming a corner by changing the crystal orientation included angle of the two p-type semiconductors; a built-in electric field is used for driving photon-generated carrier separation, so that the infrared detector works in a photovoltaic mode.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectric detection, and particularly relates to a polarization-dependent bipolar infrared detector based on a corner heterojunction, a preparation method and a photocurrent response polarity control method. BACKGROUND

[0002] The development of modern science and technology is strongly dependent on high-dimensional and intelligent interpretation of optical information, which requires the information bridge of photoelectric conversion, i.e., photoelectric detectors, to have more powerful functions. Especially under the driving of complex scenes such as sensing and calculation integration, secure communication and bionic vision, a new type of photoelectric detector emerges as the times require, the core of which is to actively reverse the response polarity according to the properties (power, wavelength, polarization) of incident light and an applied electric field. The bipolar photoelectric detector not only adds a new regulation and control dimension to the photoelectric conversion process, but also enables the detector to simultaneously analyze multiple physical information from a simple optical interaction, greatly enriching the sensing ability of optical physical processes.

[0003] The bipolar optical response of two-dimensional materials has become a frontier topic in photoelectric research, and people have explored various mechanisms to realize the reversible switching between positive and negative photocurrents. Among the many regulation strategies, gate voltage modulation as an effective means can control the direction of the built-in electric field by adjusting the interface energy level arrangement or balance a variety of complex response mechanisms. However, this method relies on external electrical bias, which will limit the processing speed and increase the complexity of large-scale integration. The wavelength-dependent molecular adsorption / desorption process can realize the reversible doping of the photosensitive layer, thereby inducing the response polarity to reverse, but this method has problems such as high environmental sensitivity, dependence on defect states, poor controllability and slow response speed. On the other hand, twisted van der Waals heterojunctions that break structural inversion symmetry can activate bulk photovoltaic effect, generating bipolar photocurrent without bias, but the polarity of photocurrent caused by this effect is usually unevenly distributed in different stacking domains, making it difficult to achieve controllable polarity switching at the device level. In addition, designed metasurfaces can provide another path by regulating light-matter interaction and polarization-sensitive bipolar response, but their working bandwidth is usually limited to a narrow spectral range. Therefore, developing a bipolar photoelectric detector with full optical control, precise adjustment, fast response and wide working bandwidth characteristics is still a key goal to promote the development of optical computing and neuromorphic computing platforms. SUMMARY

[0004] Invention purposes: In view of the problems of poor controllability, slow response speed and narrow response band of the existing bipolar photodetector based on two-dimensional material, the application provides a polarization-dependent bipolar infrared detector based on corner heterojunction, a preparation method and a photocurrent response polarity control method. By constructing a van der Waals heterojunction back-to-back diode, a polarization-dependent photocurrent bipolar response photodetector is realized. By changing the angle of the incident linearly polarized light, the polarity of the photodetector photocurrent is controlled.

[0005] Technical scheme: In a first aspect, the application provides a polarization-dependent bipolar infrared detector based on corner heterojunction, comprising: a substrate and a corner van der Waals heterojunction and a transferable metal electrode stacked on the substrate from bottom to top; the corner van der Waals heterojunction is formed by stacking p-type semiconductor, n-type semiconductor and p-type semiconductor in sequence to form npn junction, and is obtained by changing the corner angle of the two p-type semiconductors; the built-in electric field drives the separation of photo-generated carriers, so that the infrared detector works in photovoltaic mode.

[0006] Further, the p-type semiconductor is black phosphorus.

[0007] Further, the n-type semiconductor is bismuth selenide.

[0008] Further, the corner angle of the two p-type semiconductors is determined in combination with polarization Raman spectrum.

[0009] Further, the substrate is a silicon substrate with an oxide covered on the surface.

[0010] In a second aspect, the application provides a preparation method of a polarization-dependent bipolar infrared detector based on corner heterojunction, comprising the following steps: Preparation of metal electrode; Growth of bismuth selenide nanosheet; Obtaining black phosphorus film, forming corner by changing the corner angle of the two black phosphorus films; Transferring the black phosphorus film, bismuth selenide nanosheet and black phosphorus film to the substrate in sequence, and finally transferring the metal electrode to the black phosphorus film to obtain the polarization-dependent bipolar infrared detector based on corner heterojunction.

[0011] Further, the corner angle of the two black phosphorus films is determined in combination with polarization Raman spectrum.

[0012] Further, the substrate is a silicon substrate with an oxide covered on the surface.

[0013] In a third aspect, the application provides a photocurrent response polarity control method of infrared detector, comprising: Building an infrared detector, the infrared detector is a polarization-dependent bipolar infrared detector based on corner heterojunction; By changing the polarization angle of the incident light incident to the infrared detector, the polarity of the photocurrent response of the infrared detector is regulated.

[0014] Further, the polarization angle of the incident light is changed by a linear polarizer and a half-wave plate.

[0015] Beneficial effects: The present application provides a polarization-dependent bipolar infrared detector based on a corner heterojunction, a preparation method, and a photocurrent response polarity regulation method, which includes a substrate and a corner van der Waals heterojunction and a transferable metal electrode stacked on the substrate from bottom to top; the corner van der Waals heterojunction is formed by stacking black phosphorus, bismuth selenide, and black phosphorus in sequence to form an npn junction, and the corner van der Waals heterojunction is formed by changing the included angle of the black phosphorus at the bottom and the top; the present application uses the infrared polarization absorption characteristics of narrow-bandgap black phosphorus to design a back-to-back bipolar infrared detector based on a corner van der Waals heterojunction. By changing the polarization direction of the incident light, the light absorption balance of the double-layer black phosphorus is actively broken, and the photocurrent competition ratio of the two diodes is regulated to realize the switching of the net output photocurrent polarity; the present application has the advantages of simple and convenient process, wide waveband, high speed, and external voltage-free bipolar infrared detection, and provides a new design idea for developing a new type of bipolar infrared detector. Compared with the prior art, the present application has the following advantages: (1) The present application constructs a back-to-back diode structure based on a corner van der Waals heterojunction, and under the condition of no external electric field, the light response polarity switching in photovoltaic mode can be realized only by adjusting the polarization angle of the incident light, thereby simplifying the regulation mode.

[0016] (2) The present application selects black phosphorus as an infrared polarization-sensitive material, and realizes wide-spectrum bipolar light response in the near-infrared to mid-infrared waveband by combining the corner van der Waals heterojunction design, thereby effectively expanding the applicable spectral range of the bipolar photodetector and overcoming the limitation of the response waveband in the prior art.

[0017] (3) The present application uses the built-in electric field of the device to realize efficient separation of photo-generated carriers, and obtains a fast response time of 4.3 microseconds, which is superior to the response speed of bipolar photodetectors based on synaptic mechanisms or defect engineering, and is beneficial to high-speed photoelectric applications. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A structure diagram of a polarization-dependent bipolar infrared detector based on a corner heterojunction is provided for the embodiments of the present application. Figure 2 A polarization-dependent Raman intensity ratio of the top and bottom black phosphorus in a polarization-dependent bipolar infrared detector based on a corner heterojunction is provided for the embodiments of the present application. Figure 3A polarization-dependent bipolar infrared detector based on a corner heterojunction and a polarization angle-dependent light response curve of a single heterojunction polarization detector are compared for an embodiment of the present application, wherein Figure 3 (a) in the above is a polarization-dependent bipolar response of the corner heterojunction detector, Figure 3 (b) in the above is a polarization-dependent bipolar response of the single heterojunction detector. Figure 4 A power-dependent response curve of a polarization-dependent bipolar infrared detector based on a corner heterojunction under mid-infrared incident light of different polarization directions is provided for an embodiment of the present application. Figure 5 A response speed curve of a polarization-dependent bipolar infrared detector based on a corner heterojunction is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be further described in combination with the drawings and embodiments.

[0020] Embodiment one: The present application provides a polarization-dependent bipolar infrared detector based on a corner heterojunction, which comprises a substrate and a corner van der Waals heterojunction and a transferable metal electrode stacked in order from bottom to top on the substrate; the corner van der Waals heterojunction is formed by stacking black phosphorus, bismuth selenide and black phosphorus in order to form an npn junction, and the corner van der Waals heterojunction is formed by changing the angle between the bottom and top black phosphorus crystal orientations.

[0021] In the embodiment of the present application, the substrate is a silicon substrate with an oxide-covered surface, and the transferable metal electrode is a gold electrode.

[0022] When the bias voltage of the transferable metal electrode is 0 V, the bipolar photodetector provided in the embodiment of the present application works in photovoltaic mode.

[0023] Embodiment two: The present application provides a preparation method of a polarization-dependent bipolar infrared detector based on a corner heterojunction, comprising the following steps: A gold electrode is prepared on a cleaned pure silicon wafer by a standard laser lithography process and a thermal evaporation process, HMDS is dropped on the pure silicon wafer with the gold electrode, and it is placed on a 120℃ hot plate, after 10 minutes, it is taken out, a layer of PMMA is spin-coated on its surface, the gold electrode is lifted off from the pure silicon wafer with PDMS, and it is ready for use; Bismuth selenide oxide nanosheets were deposited on a mica substrate using chemical vapor deposition. PMMA was then spin-coated onto the mica sheet containing the bismuth selenide oxide nanosheets. The PMMA was then transferred to a pure silicon wafer using a wet transfer method with HF solution-assisted etching. The wafer was heated to 120°C for 5 minutes, and the PMMA was washed away with acetone. HMDS was then dropped onto the pure silicon wafer containing the bismuth selenide oxide nanosheets and placed on a hot plate at 120°C. After 10 minutes, the wafer was removed, a layer of PMMA was spin-coated onto its surface, and the bismuth selenide oxide nanosheets were extracted from the pure silicon wafer using PDMS for later use. Two black phosphorus films were obtained by mechanical exfoliation, and their crystal orientations were determined by polarized Raman spectroscopy. Black phosphorus film, bismuth selenide oxide nanosheets, and black phosphorus film were sequentially transferred onto the substrate using a dry transfer method. The crystal orientations of the bottom and top black phosphorus films were perpendicular to each other. Then, the prepared gold electrode was transferred over the two black phosphorus films. The fabricated device was annealed on a hot plate at 180 °C for 30 minutes to obtain a polarization-dependent bipolar infrared detector based on a corner heterojunction.

[0024] Example 3: Figure 1 As shown, this embodiment of the invention proposes a polarization-dependent bipolar infrared detector based on a corner heterojunction, which mainly includes: a silicon substrate 1 with an oxide layer, a black phosphorus 2 at the bottom, a bismuth selenide oxide 3, a black phosphorus 4 at the top, a first transferable metal electrode 5, and a second transferable metal electrode 6.

[0025] The n-type semiconductor bismuth selenide 3 forms a back-to-back diode with the bottom black phosphorus 2 and the top black phosphorus 4 respectively. In this embodiment, the n-type semiconductor bismuth selenide 3 and the p-type semiconductor black phosphorus form a pn junction. The built-in electric field drives the separation of photogenerated carriers, so that the device can work in photovoltaic mode.

[0026] In this embodiment of the invention, bottom black phosphorus 2 and top black phosphorus 4 of similar thickness are selected to ensure balanced light absorption capacity and form a built-in electric field with matching intensity.

[0027] Specifically, in this embodiment of the invention, the thickness of the top black phosphorus 4 is approximately 40 nm, the thickness of the bismuth selenide oxide 3 is approximately 185 nm, and the thickness of the top black phosphorus 4 is approximately 45 nm.

[0028] Specifically, in this embodiment of the invention, the first transferable metal electrode 5 and the second transferable metal electrode 6 are both gold electrodes with a thickness of 50 nm. When the bias voltage applied between the first transferable metal electrode 5 and the second transferable metal electrode 6 is 0V, the detector operates in photovoltaic mode.

[0029] The embodiment of the present application combines a linear polarizer and a half-wave plate to change the polarization angle of incident light, and the crystal direction of the black phosphorus film prepared by exfoliation is determined by the intensity ratio of Raman signals.

[0030] The embodiment of the present application works based on the reverse built-in electric field in the back-to-back double-diode structure. The core mechanism is that the change of the polarization direction of incident light breaks the light absorption balance of the top and bottom black phosphorus, thereby correspondingly changing the amplitude ratio of the photocurrent generated by the two diodes. The ratio change finally shows the switching of the polarity of the net output photocurrent, realizing the effect of controlling the response polarity by only adjusting the polarization angle of the incident light.

[0031] The detector proposed in the embodiment of the present application is packaged with electron beam evaporated aluminum oxide (20 nm) and works in room temperature and atmospheric environment, and its detection wave band covers near-infrared to mid-infrared.

[0032] Embodiment four: the embodiment of the present application proposes a preparation method of a polarization-dependent bipolar infrared detector based on a corner heterojunction, which mainly includes the following steps: Step 1: a common pure silicon wafer is sequentially cleaned by acetone, isopropyl alcohol and deionized water; Step 2: a gold electrode with a thickness of 30 nm is prepared on the common pure silicon wafer by a standard laser lithography process and a thermal evaporation process; the silicon wafer with the gold electrode is dropped with HMDS and placed on a 120 DEG C hot plate for 10 minutes, then a layer of PMMA is spin-coated on the surface, the gold electrode is lifted off from the silicon wafer by using PDMS, and the silicon wafer with the gold electrode is prepared for use; Step 3: selenium bismuth oxide nanosheets are grown on a mica substrate by chemical vapor deposition, PMMA is spin-coated on the mica substrate with the selenium bismuth oxide nanosheets, and 7% hydrofluoric acid diluent is used to etch the mica substrate, and the PMMA film with the selenium bismuth oxide is transferred to the pure silicon wafer by wet transfer, and placed on a 120 DEG C hot plate for 5 minutes.

[0033] Step 4: the pure silicon wafer with the selenium bismuth oxide is dropped with HMDS and placed on a 120 DEG C hot plate for 10 minutes, then a layer of PMMA is spin-coated on the surface, the selenium bismuth oxide nanosheet is lifted off from the silicon wafer by using PDMS, and the silicon wafer with the selenium bismuth oxide is prepared for use; Step 5: a black phosphorus film is obtained by mechanical exfoliation, and the crystal direction of the black phosphorus film is determined by the polarization-dependent Raman peak intensity ratio.

[0034] Step 6: the black phosphorus film, the selenium bismuth oxide nanosheet and the black phosphorus film are transferred to the silicon substrate with the oxide layer by dry transfer in turn, and finally the prepared gold electrode is transferred to the black phosphorus film to obtain the device.

[0035] Step 7: The prepared device was annealed on a hot plate at 180 ℃ for 15 minutes to obtain a polarization-dependent ambipolar infrared detector based on a corner heterojunction.

[0036] Figure 2 The polarization-dependent Raman peak intensity ratio of the top and bottom black phosphorus in the corner heterojunction detector prepared in this embodiment is given, and it can be seen that there is a significant difference in the crystal direction between the top black phosphorus and the bottom black phosphorus, and the included angle between them is about 90°.

[0037] Figure 3 The polarization-dependent optical response of the ambipolar infrared detector based on the corner heterojunction and the single heterojunction device is given. Among them, Figure 3 (a) in FIG. 13 is the polarization-dependent ambipolar response of the corner heterojunction detector under zero bias voltage at 1350 nm incident light, and the device shows a positive-negative alternating optical response similar to a sine function as the incident light polarization angle changes; Figure 3 (b) in FIG. 13 is the polarization-dependent optical response of the single heterojunction detector, and the device shows a single positive optical response as the incident light polarization angle changes. The change of the incident light polarization direction breaks the light absorption balance of the double-layer black phosphorus, thereby changing the competition relationship of the photoelectric current of the two reverse diodes. The net output polarity is determined by the dominant photoelectric current direction, thereby realizing the polarization-dependent ambipolar photoelectric response. The single heterojunction cannot realize polarity switching due to the lack of such internal competition mechanism, and only shows a unipolar optical response behavior.

[0038] Figure 4 The ambipolar response of the polarization-dependent ambipolar infrared detector based on the corner heterojunction prepared in this embodiment under mid-wave infrared light is given. It can be seen that under 3500 nm mid-wave infrared light, the device produces an ambipolar response to two perpendicular polarized lights at zero bias voltage, which verifies the advantage of black phosphorus narrow bandgap semiconductor material in mid-wave infrared detection. At the same time, both the positive and negative photoelectric currents show a clear dependence on the incident light power.

[0039] Figure 5 The response speed curve of the polarization-dependent ambipolar infrared detector based on the corner heterojunction prepared in this embodiment under 633 nm incident light is given. The rise time and fall time are defined as the time when the photoelectric current increases from 10% to 90% and decreases from 90% to 10%, respectively. The rise and fall times of the device are 4.3 μs and 7.5 μs, respectively, which are better than those of the ambipolar photodetector based on the synaptic mechanism or defect engineering.

Claims

1. A polarization-dependent bipolar infrared detector based on a corner heterojunction, characterized in that: include: A substrate and a corner van der Waals heterojunction and a transferable metal electrode stacked sequentially on the substrate from bottom to top; The corner van der Waals heterojunction is formed by stacking p-type semiconductors, n-type semiconductors, and p-type semiconductors in sequence to form an npn junction. The corner is obtained by changing the angle between the crystal orientations of the two p-type semiconductors. The infrared detector operates in photovoltaic mode by driving the separation of photogenerated carriers through a built-in electric field.

2. The polarization-dependent bipolar infrared detector based on a corner heterojunction according to claim 1, characterized in that: The p-type semiconductor is black phosphorus.

3. A polarization-dependent bipolar infrared detector based on a corner heterojunction according to claim 1, characterized in that: The n-type semiconductor is bismuth selenide oxide.

4. A polarization-dependent bipolar infrared detector based on a corner heterojunction according to claim 1, characterized in that: The angle between the crystal orientations of the two p-type semiconductors was determined by combining polarized Raman spectroscopy.

5. A polarization-dependent bipolar infrared detector based on a corner heterojunction according to claim 1, characterized in that: The substrate is a silicon substrate with an oxide coating on its surface.

6. A method for fabricating a polarization-dependent bipolar infrared detector based on a corner heterojunction, characterized in that: Includes the following steps: Preparation of metal electrodes; Growth of bismuth oxide selenium nanosheets; A black phosphorus film was obtained by changing the angle between the crystal orientations of two black phosphorus films to form a rotation angle. Black phosphorus film, bismuth selenide oxide nanosheets and black phosphorus film were sequentially transferred onto a substrate, and finally a metal electrode was transferred onto the black phosphorus film to obtain a polarization-dependent bipolar infrared detector based on a corner heterojunction.

7. The method for fabricating a polarization-dependent bipolar infrared detector based on a twist heterojunction according to claim 6, characterized in that: The crystal orientation angle between the two black phosphorus films was determined by combining polarized Raman spectroscopy.

8. The method for fabricating a polarization-dependent bipolar infrared detector based on a corner heterojunction according to claim 6, characterized in that: The substrate is a silicon substrate with an oxide coating on its surface.

9. A method for controlling the polarity of the photocurrent response of an infrared detector, characterized in that: include: An infrared detector is constructed, wherein the infrared detector is a polarization-dependent bipolar infrared detector based on a corner heterojunction as described in any one of claims 1 to 5. The polarization angle of the incident light incident on the infrared detector is changed to modulate the photocurrent response polarity of the infrared detector.

10. The method for controlling the polarity of the photocurrent response of an infrared detector according to claim 9, characterized in that: The polarization angle of incident light can be changed by using linear polarizers and half-wave plates.

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