Infrared polarization detector based on anisotropic light-gating manipulation and preparation process thereof

Abstract

The present application relates to the technical field of polarization detector, and particularly relates to an infrared polarization detector based on anisotropic light gate control and a preparation process thereof. In order to solve the technical problem that it is difficult to realize high polarization resolution and high sensitivity in a wide wavelength range while keeping the structure of the polarization detector simple. Technical scheme: the super high extinction ratio infrared polarization detector comprises a local gate layer arranged above a bottom substrate layer; a dielectric layer arranged above the local gate layer; a source electrode layer or a drain electrode layer arranged above the dielectric layer, and another electrode layer arranged above the bottom substrate layer; a two-dimensional material layer arranged above the source electrode layer and the drain electrode layer; the dielectric layer material and the bottom substrate layer material are different in the number of bound states; the two-dimensional material layer is an anisotropic material; a part of the two-dimensional material layer is in contact with the bottom substrate layer, and another part is in contact with the dielectric layer.

Description

Technical Field

[0001] This invention relates to the field of polarization detector technology, specifically to an infrared polarization detector based on anisotropic optical gating and its fabrication process. Background Technology

[0002] As one of the fundamental properties of light, polarization has attracted much attention in almost all fields of optical science and technology because the interaction of light with matter depends to a large extent on the polarization state of light. Polarization detection provides an additional dimension of information, different from intensity and wavelength detection, and plays a crucial role in many applications.

[0003] Among the numerous studies dedicated to the miniaturization and integration of polarization detectors, filterless integrated polarization detectors have attracted considerable attention in recent years. Especially in the area of ​​photon-electron co-manipulation, these devices can achieve polarization extinction ratios covering the entire possible range (1 → ∞ / -∞ → -1), providing enormous potential for the development of high-performance integrated polarization detectors.

[0004] These (∞ / -∞)-PER detectors are typically made of two-dimensional van der Waals materials integrated with nanoantennas or specific heterostructures. They enhance polarization detection capabilities through the vector photothermal current superposition effect induced by nanoantenna resonance, or through the band distribution and unique absorption spectrum in specific heterostructures.

[0005] Filterless integrated polarization detectors hold significant promise for next-generation ultracompact optical and optoelectronic systems, particularly demonstrating substantial advantages in integrated, portable, and high-efficiency polarization detection systems. Nevertheless, the device structure remains relatively complex. Further optimization of the detector structure and achievement of high polarization resolution and high sensitivity across a wide wavelength range still present numerous challenges.

[0006] To further improve the overall performance of filterless integrated polarization detectors, researchers are working to achieve ultra-high polarization resolution and high sensitivity while maintaining a simple device structure, and simultaneously expanding the wavelength range they can detect. Although this goal is extremely challenging, it opens up entirely new directions for the advancement of polarization detector technology and its practical applications.

[0007] Black phosphorus (BP) is one of the representative van der Waals materials. From a crystal structure perspective, black phosphorus (BP) has a layered structure similar to graphene in the vertical direction and exhibits extremely high hole and electron mobilities (350 cm⁻¹, respectively) at room temperature. 2 V -1 s -1 and 220 cm 2 V -1 s -1Black phosphorus (BP) has thus attracted widespread attention in the fields of electronics and optoelectronics. As a direct bandgap semiconductor, BP has a bulk bandgap of approximately 0.3 eV under conventional conditions, and thin layers obtained through mechanical exfoliation typically exhibit p-type doping characteristics. Furthermore, black phosphorus exhibits an asymmetric honeycomb structure in the plane, resulting in significant anisotropy in its electrical, optical, and thermal conductivity properties. This unique anisotropy makes BP an ideal material for fabricating mid-infrared polarization photodetectors. Utilizing the excellent electronic and optical properties of black phosphorus, it is hoped that high-sensitivity polarization detection can be achieved in the infrared band.

[0008] Optical gating-induced conductivity changes are a well-known effect that can enable ultra-high gain in phototransistors. This effect typically occurs at the interface between low-dimensional materials or their supporting substrates, where bound photocarriers generate additional gate voltages, thereby electrostatically modulating the material itself. Summary of the Invention

[0009] The purpose of this invention is to provide an infrared polarization detector based on anisotropic optical gating and its fabrication process, in order to solve the technical problem of "it is difficult to achieve both ultra-high polarization resolution and high sensitivity over a wide wavelength range while maintaining the simplicity of the polarization detector structure".

[0010] The inventors overcame the challenge of achieving both high polarization resolution and high sensitivity over a wide wavelength range by discovering and utilizing a novel effect of intrinsic anisotropic optical gating-induced band modulation.

[0011] Terminology Explanation:

[0012] Unless otherwise defined, all technical terms in this document have the same meanings as commonly understood by one of ordinary skill in the art to which the subject matter of the claims pertains. Unless otherwise stated, all patents, patent inventions, and publications cited in this document are incorporated herein by reference in their entirety. If multiple definitions exist for terms in this document, the definitions in this chapter shall prevail.

[0013] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0014] To achieve the above objectives, the technical solution of the present invention is as follows:

[0015] Firstly,

[0016] This invention provides an ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating, comprising a bottom substrate layer, a local gate layer, a dielectric layer, a source electrode layer, a drain electrode layer, and a two-dimensional material layer; the local gate layer is disposed above the bottom substrate layer; the dielectric layer is disposed above the local gate layer; either the source electrode layer or the drain electrode layer is disposed above the dielectric layer, and the other electrode layer of the source electrode layer or the drain electrode layer is disposed above the bottom substrate layer;

[0017] A two-dimensional material layer is disposed above the source electrode layer and the drain electrode layer, and the two-dimensional material layer is connected to the source electrode layer and the drain electrode layer respectively; or, the two-dimensional material layer is disposed above the dielectric layer and the bottom substrate layer, and the source electrode layer and the drain electrode layer are disposed above the two-dimensional material layer.

[0018] The number of bound states differs between the dielectric layer material and the bottom substrate material; the two-dimensional material layer is anisotropic; part of the two-dimensional material layer is in contact with the bottom substrate layer, and another part is in contact with the dielectric layer.

[0019] In some embodiments, the bottom substrate layer is a support layer with a thickness of h0.

[0020] In some embodiments, the bottom substrate layer is made of materials including, but not limited to, semiconductor process substrate materials such as Si, GaAs, GaN, and Al2O3.

[0021] In some embodiments, the local gate layer is a conductive material with a thickness of h1, where h1 ranges from 1 to 100 nm.

[0022] The local gate layer has a certain width d1 in the horizontal direction, which ranges from 5 to 20 μm.

[0023] In some embodiments, the local gate layer is made of a metallic material including, but not limited to, gold, silver, aluminum and their alloys, or graphene.

[0024] In some embodiments, the dielectric layer is a dielectric material with a thickness h2 and is non-conductive; h2 ranges from 10 to 100 nm.

[0025] The dielectric layer has a width d2 in the horizontal direction, which is 0-10 μm wider than the width d1 of the local gate layer. The centers of the dielectric layer and the local gate layer coincide in the horizontal direction.

[0026] In some embodiments, the dielectric layer is made of materials including, but not limited to, hBN, SrTiO3, Sb2O3, HfO2, and Al2O3.

[0027] In some embodiments, the material of the dielectric layer may be the same as or different from the material of the bottom substrate layer.

[0028] In some embodiments, the number of bound states of the dielectric layer material and the bottom substrate layer material differs, and the ratio of the number of bound states between the two is ≥2.

[0029] The number of bound states in the dielectric layer material is not necessarily less than the number of bound states in the bottom substrate material; it can be greater.

[0030] In some embodiments, in the source electrode layer and the drain electrode layer, the channel width between the two electrode regions of the source electrode layer and the drain electrode layer is d3, the channel width d3 is greater than the width d1 of the local gate layer, and the range of d3 is 20-100 μm.

[0031] In some embodiments, the two-dimensional material layer is anisotropic material, including but not limited to two-dimensional semiconductors and two-dimensional semi-metallic materials, and the two-dimensional material layers are bonded by van der Waals forces, including but not limited to black phosphorus, tellurene, and WTe2.

[0032] Secondly,

[0033] This invention provides a fabrication process for an infrared polarization detector based on anisotropic optical gating, comprising:

[0034] After immersing the bottom substrate layer in acetone, isopropanol, and deionized water and sonicating for a certain period of time, the surface is dried with nitrogen.

[0035] The pattern of the local gate layer is defined on the bottom substrate using ultraviolet lithography through three steps: coating, photolithography, and development. Metals Ti and Au are deposited sequentially using electron beam evaporation or thermal evaporation to form a film. The coated sample is then placed in acetone for peeling to obtain the local gate layer.

[0036] The dielectric layer is obtained from the single crystal dielectric material using mechanical stripping and transferred onto the local gate layer using dry transfer technology. Alternatively, the dielectric layer can be obtained directly using atomic layer deposition and the pattern of the dielectric layer can be defined using ion beam etching.

[0037] The source electrode layer and drain electrode layer are patterned on the bottom substrate layer after the local gate layer and dielectric layer are prepared by ultraviolet lithography through three steps: coating, photolithography and development. Metal Ti and Au are deposited sequentially by electron beam evaporation or thermal evaporation to form a film. Then the coated sample is placed in acetone for peeling to obtain the source electrode layer and drain electrode layer.

[0038] Two-dimensional material layers were obtained from single-crystal two-dimensional material samples using mechanical exfoliation, and then transferred onto the source electrode layer and drain electrode layer using dry transfer technology.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] This invention relates to an ultra-high extinction ratio infrared polarization detector where the number of bound states differs between the dielectric layer material and the bottom substrate material; the two-dimensional material layer is anisotropic; a portion of the two-dimensional material layer is in contact with the bottom substrate layer, and another portion is in contact with the dielectric layer. The two-dimensional material layer has two contact interfaces: one side is the bottom substrate layer containing bound states, and the other side is the dielectric layer with almost no bound states. Under illumination, the polarization state of the incident light can significantly adjust the band structure of the ultra-high extinction ratio infrared polarization detector, thereby directly affecting the self-driven photocurrent.

[0041] Based on the novel effect of intrinsic anisotropic photogating-induced band modulation, the ultra-high extinction ratio infrared polarization detector of this invention can approach ∞ / -∞ in the near-infrared to mid-infrared band. Compared with other polarization detectors that achieve similar (∞ / -∞)‐PER performance, the ultra-high extinction ratio infrared polarization detector achieves the highest levels in both peak power ratio detectivity and blackbody ratio detectivity, thereby greatly improving the polarization resolution and sensitivity of the polarization detector.

[0042] The present invention provides an ultra-high extinction ratio infrared polarization detector that can respond to blackbody radiation at temperatures as low as 468 K, and can still achieve PER = ∞ / -∞ under this temperature condition.

[0043] Its specific polarization angle detectivity reaches 3 × 10⁻⁶. 7 Jones degree -1 This is two to four orders of magnitude faster than existing polarization detectors. Although this (BP / hBN)-(BP / SiO2) homojunction detector utilizes optical gating to modulate the band structure, its optical response time remains in the microsecond range, demonstrating excellent dynamic response capabilities. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0045] Figure 1 A schematic diagram of the structure of the ultra-high extinction ratio infrared polarization detector of the present invention.

[0046] Figure 2 A front view of the ultra-high extinction ratio infrared polarization detector of the present invention.

[0047] Figure 3 A top view of the ultra-high extinction ratio infrared polarization detector of the present invention.

[0048] Figure 4 A schematic diagram of the band structure of BP and the bound states in SiO2 in a dark environment. + Represents an empty cavity;

[0049] Figure 5 In a dark environment, V g A schematic diagram of charge trapping and built-in electric field inside the (BP / hBN)-(BP / SiO2) homojunction at 0 V;

[0050] Figure 6 In a dark environment, V g A schematic diagram of the band structure inside the (BP / hBN)-(BP / SiO2) homojunction at 0 V.

[0051] Figure 7 A schematic diagram of the charge binding and built-in electric field inside a (BP / hBN)-(BP / SiO2) homojunction under illumination; the wavelength of the incident light is 3.3 μm, and the power density is 45 mW cm⁻¹. -2 , V g = 5.2 V; polarization angle is 0°;

[0052] Figure 8 A schematic diagram of the energy band structure inside a (BP / hBN)-(BP / SiO2) homojunction under illumination; the wavelength of the incident light is 3.3 μm, and the power density is 45 mW / cm². -2 , V g = 5.2 V; polarization angle is 0°.

[0053] Figure 9 A schematic diagram of the charge binding and built-in electric field inside a (BP / hBN)-(BP / SiO2) homojunction under illumination; the wavelength of the incident light is 3.3 μm, and the power density is 45 mW cm⁻¹. -2 , V g = 5.2 V; polarization angle is 90°;

[0054] Figure 10 A schematic diagram of the energy band structure inside a (BP / hBN)-(BP / SiO2) homojunction under illumination; the wavelength of the incident light is 3.3 μm, and the power density is 45 mW / cm². -2 , V g = 5.2 V; polarization angle is 90°.

[0055] Figure 11 The (BP / hBN)-(BP / SiO2) homojunction detector in the dark state (optical power density of 0.0 mW / cm²) -2 ) and 3.3 μm wavelength illumination I ds - V ds Curve graph

[0056] The optical power density varies within a range of 2.2 mW / cm². -2 Up to 37 mW cm -2 .

[0057] Figure 12 Measurements taken at different incident light polarization angles Vg The curve of the self-driven photocurrent dependent on the incident light wavelength of 3.3 μm and the power density of 65 mW / cm². -2 ;

[0058] Figure 13 , V g Plots of polarization-dependent self-driven photocurrent at 0 V and 5.3 V; incident light wavelength 3.3 μm, power density 65 mW / cm². -2 ;

[0059] Figure 14 , V g The graphs show the polarization-dependent self-driven photocurrent at 0 V and 5.2 V; the incident light wavelength is 2.2 μm.

[0060] Figure 15 , V g The graphs show the polarization-dependent self-driven photocurrent at 0 V and 4.5 V; the incident light wavelength is 1.55 μm.

[0061] Figure 16 Noise current spectrum measured under dark conditions or under different polarized light illumination. V g = 5.3 V, incident light wavelength is 3.3 μm, power density is 65 mW cm⁻¹ -2 ; V ds = 0 V.

[0062] Figure 17 (BP / hBN)-(BP / SiO2) homojunction detector V g Polarization-dependent extinction ratio curve; incident light wavelength is 3.3 μm, power density is 65 mW / cm². -2 .

[0063] Figure 18 Temperature-dependent responsivity and specific detectivity curves for (BP / hBN)-(BP / SiO2) homojunction detectors; blackbody temperature range from 468 K to 1268 K.

[0064] Figure 19 Measured at polarization angles of 0°, 30° and 90° respectively. V g The self-driven photocurrent curve; the light source is blackbody radiation, and the temperature of the blackbody is 1268 K;

[0065] Figure 20 Under blackbody radiation, V g Polarization-dependent photocurrent curves at 0 V and 4 V; blackbody temperature is 1268 K.

[0066] Figure 21 Self-driven photocurrent waveform. Rise time t r The fall time is 4.4 μs, and the descent time is t. f The wavelength of the incident light is 4.3 μs; the wavelength of the incident light is 3.3 μm; and the power density is 65 mW / cm². -2 .

[0067] Explanation of reference numerals in the attached figures:

[0068] 1. Bottom substrate layer; 2. Localized gate layer; 3. Dielectric layer; 4-1. Source electrode layer; 4-2. Drain electrode layer; 5. Two-dimensional material layer. Detailed Implementation

[0069] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0070] It should be noted that, unless otherwise specifically stated, the relative arrangement and numerical expressions of the components and steps described in these embodiments should not be construed as limiting the scope of the invention.

[0071] The following description of exemplary embodiments is merely illustrative and is not intended to limit the invention or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail herein, but where applicable, such techniques, methods, and apparatus should be considered part of this specification.

[0072] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0073] For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves. They do not limit the structure and are merely for the purpose of facilitating the description of this invention and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0074] Terminology Explanation: The terms "installation," "connection," "linking," and "fixing" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction relationship between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075]

[0076] Example 1

[0077] Combination Figures 1-3 As shown, the ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating provided by the present invention includes a bottom substrate layer 1, a local gate layer 2, a dielectric layer 3, a source electrode layer 4-1, a drain electrode layer 4-2, and a two-dimensional material layer 5.

[0078] The local gate layer 2 is disposed above the bottom substrate layer 1 and is located on one side of the bottom substrate layer 1; the dielectric layer 3 is disposed above the local gate layer 2;

[0079] The positions of the source electrode layer 4-1 and the drain electrode layer 4-2 can be interchanged. The source electrode layer 4-1 or the drain electrode layer 4-2 is disposed above the dielectric layer 3. The other electrode layer of the source electrode layer 4-1 or the drain electrode layer 4-2 is disposed above the bottom substrate layer 1 and is located on the other side of the bottom substrate layer 1, away from the local gate layer 2. A certain gap is left between the source electrode layer 4-1 or the drain electrode layer 4-2 located above the bottom substrate layer 1 and the local gate layer 2.

[0080] A two-dimensional material layer 5 is disposed above the source electrode layer 4-1 and the drain electrode layer 4-2, and the two-dimensional material layer 5 is connected to the source electrode layer 4-1 and the drain electrode layer 4-2 respectively.

[0081] In other embodiments, the positions of the two-dimensional material layer 5, the source electrode layer 4-1, and the drain electrode layer 4-2 can be interchanged. That is, the two-dimensional material layer 5 is disposed above the dielectric layer 3 and the bottom substrate layer 1, and the source electrode layer 4-1 and the drain electrode layer 4-2 are disposed above the two-dimensional material layer 5.

[0082] The bottom substrate layer 1 is the support layer for the entire ultra-high extinction ratio infrared polarization detector, with a thickness of h0.

[0083] The bottom substrate layer 1 is made of semiconductor process substrate materials including but not limited to Si, GaAs, GaN, and Al2O3.

[0084] The local gate layer 2 is a highly conductive material with a thickness of h1, where h1 ranges from 1 to 100 nm; the local gate layer 2 has a certain width d1 in the horizontal direction, which ranges from 5 to 20 μm.

[0085] The local gate layer 2 may be made of metallic materials including but not limited to gold, silver, aluminum and their alloys, or two-dimensional materials such as graphene.

[0086] The dielectric layer 3 is a dielectric material with a thickness h2 and is non-conductive; h2 ranges from 10 to 100 nm; the dielectric layer 3 has a width d2 in the horizontal direction, which is 0 to 10 μm wider than the width d1 of the local gate layer 2, and the center of the dielectric layer 3 coincides with the center of the local gate layer 2 in the horizontal direction.

[0087] The dielectric layer 3 is made of materials including but not limited to hBN, SrTiO3, Sb2O3, HfO2, and Al2O3.

[0088] The material of dielectric layer 3 can be the same as or different from the material of the bottom substrate layer 1, provided that both are insulating and have different numbers of bound states inside.

[0089] The number of bound states in dielectric layer 3 differs from that in the bottom substrate layer 1, with the ratio of the number of bound states being ≥2. The number of bound states in dielectric layer 3 is not necessarily less than that in the bottom substrate layer 1; it can be greater. For example, the materials of dielectric layer 3 and bottom substrate layer 1 may be different: dielectric layer 3 is hBN, while bottom substrate layer 1 is SiO2.

[0090] In the source electrode layer 4-1 and the drain electrode layer 4-2, the channel width between the two electrode regions of the source electrode layer 4-1 and the drain electrode layer 4-2 is d3. The channel width d3 is greater than the width d1 of the local gate layer 2. The range of d3 is 20-100 μm.

[0091] The two-dimensional material layer 5 is an anisotropic material, including but not limited to two-dimensional semiconductors and two-dimensional semi-metallic materials. The two-dimensional material layer 5 is bonded by van der Waals forces, and its types include but are not limited to black phosphorus, tellurene, and WTe2.

[0092] This invention further discovers that in intrinsically anisotropic photodetector materials such as black phosphorus (BP), the optical gating effect exhibits a significant polarization dependence. To address this, this embodiment provides an infrared polarization detector based on anisotropic optical gating manipulation. The two-dimensional material layer 5 is a thin layer of black phosphorus (BP), the dielectric layer 3 is made of hBN, the bottom substrate layer 1 uses a SiO2 / Si substrate as support, the source electrode layer 4-1 and drain electrode layer 4-2 are made of metal, and the localized gate layer 2 is also made of metal. The black phosphorus is connected to the source and drain electrodes respectively and is supported by the SiO2 / Si substrate.

[0093] To address this, the inventors fabricated a (BP / hBN)-(BP / SiO2) homojunction detector based on the materials used in the aforementioned infrared polarization detector. As a specific embodiment of the infrared polarization detector of the present invention, the (BP / hBN)-(BP / SiO2) homojunction detector has two contact interfaces in the horizontal direction: one side is SiO2 containing bound states, and the other side is hBN with almost no bound states, forming a (BP / hBN)-(BP / SiO2) homojunction; wherein hBN plays an insulating role between BP and the localized gate layer 2.

[0094] Under illumination, the polarization state of the incident light can significantly adjust the band distribution of the (BP / hBN)-(BP / SiO2) homojunction detector, thereby directly affecting the self-driven photocurrent.

[0095] A novel effect based on intrinsic anisotropic optical gating-induced band modulation.

[0096] The polarization extinction ratio (PER) of the (BP / hBN)-(BP / SiO2) homojunction detector of this invention approaches ∞ / -∞ in the near-infrared to mid-infrared band. Compared with other polarization detectors that achieve similar (∞ / -∞)-PER performance,

[0097] The (BP / hBN)-(BP / SiO2) homojunction detector achieves the highest levels in both peak detectivity and blackbody detectivity, thereby greatly improving the polarization resolution and sensitivity of the polarization detector.

[0098] More importantly, this (BP / hBN)-(BP / SiO2) homojunction detector can respond to blackbody radiation at temperatures as low as 468 K, and still achieve PER = ∞ / -∞ at this temperature. Its specific polarization angle detectivity reaches 3 × 10⁻⁶. 7 Jones degree -1 It is two to four orders of magnitude higher than existing polarization detectors.

[0099] Although the (BP / hBN)-(BP / SiO2) homojunction detector utilizes optical gating to modulate the band structure, its photoresponse time remains in the microsecond range, demonstrating excellent dynamic response capability.

[0100] The following uses the (BP / hBN)-(BP / SiO2) homojunction detector as an example to explain in detail the performance of the infrared polarization detector of the present invention. If other materials are used, as long as the defect states (bound states) of the bottom substrate layer 1 and the dielectric layer 3 are different, and the two-dimensional material layer 5 itself has anisotropy, it can have the same performance as the (BP / hBN)-(BP / SiO2) homojunction detector.

[0101] In a (BP / hBN)-(BP / SiO2) homojunction detector, the BP has two contact interfaces in the horizontal direction: one side is SiO2 containing bound states, and the other side is hBN with almost no bound states. The SiO2 substrate typically contains a large number of defects, which can act as binding centers for electrons or holes. Therefore, a large amount of charge accumulates at the BP / SiO2 interface, and holes in the BP, as the dominant charge carriers, are easily captured by the hole binding centers in the SiO2. Then, due to the interface gate control effect, the p-type doping concentration of the BP decreases. On the other hand, the hBN forms an atomically flat van der Waals interface with BP, free of dangling bonds, and has far fewer binding centers than SiO2; therefore, the BP on the hBN is almost unaffected.

[0102] like Figure 4 The diagram shows the band structure of the (BP / hBN)-(BP / SiO2) homojunction detector in a dark environment and the bound states in SiO2. The valence band maximum and conduction band minimum of BP are -5.4 eV and -5.1 eV, respectively. Since BP itself is p-type doped, the Fermi level is close to the valence band, and holes are the majority carriers. E f Located at -5.336 eV. Two bound energy levels exist in SiO2 that can trap charge; Figure 4In the BP spectrum, the electron binding band (3.46 eV) is close to the conduction band, and the hole binding band (5.92 eV) is close to the valence band. This is due to the BP Fermi level. E f Holes in BP can relatively easily transfer to the lower binding band of SiO2 and form bound charges.

[0103] like Figure 5 , Figure 6 As shown, the charges bound at the interface between black phosphorus and silicon dioxide subsequently generate an upward electrostatic field, inducing n-type doping of the BP, which in turn reduces the p-type doping of the BP on SiO2. According to the model of the (BP / hBN)-(BP / SiO2) homojunction detector in this embodiment, for the BP on SiO2, the bound charges lower its Fermi level (… E f This increased by 0.081 eV. However, since there are almost no bound states in the hBN system, the BP on hBN... E f No change. Ultimately, due to the BP on hBN and SiO2... E f The difference lies in the formation of in-plane PP at the interface between BP / hBN and BP / SiO2. - Homojunction. This pp - The built-in electric field of the homojunction can generate a self-driven photovoltaic response, with the photocurrent flowing from BP / SiO2 to BP / hBN.

[0104] When the (BP / hBN)-(BP / SiO2) homojunction detector is switched from a dark environment to an illuminated environment, the photogenerated carriers generated by the illumination will change the number and type of bound charges, thereby affecting the electrostatic control effect generated by the bound charges at the BP / SiO2 interface, and ultimately adjusting the band alignment between BP / SiO2 and BP / hBN.

[0105] Under illumination, photogenerated carriers include photogenerated holes and photogenerated electrons. For photogenerated holes, since the hole-trapping centers in the entire system are already occupied by intrinsic majority carriers (holes) in the BP (backpropagation) system in darkness, the probability of photogenerated holes being trapped is low. Photogenerated electrons, on the other hand, are captured by electron-binding centers with a relatively high probability (e.g., ...). Figure 7 As shown, a negative electrostatic field is generated, which reduces the positive electric field generated by the holes bound in the dark state, resulting in p-type doping of BP on SiO2, which weakens the homojunction effect and thus reduces the self-driven photoresponse.

[0106] Because the light absorption of BP materials is anisotropic, the band alignment effect modulated by illumination exhibits significant differences under different polarization states. Figure 7 and Figure 8 The optical modulation effect induced by incident light in a zigzag (ZZ) direction (0° polarization) is demonstrated. Figure 9 and Figure 10 This demonstrates the optical modulation effect induced by incident light in an armchair-type (AC) direction (90° polarization). The incident light power is the same in both cases. Because the absorption efficiency of BP for 0° polarized light is lower than that for 90° polarized light, fewer photogenerated carriers are generated under 0° polarization, resulting in fewer bound photogenerated electrons. Therefore, the Fermi level of BP on SiO2 decreases only slightly. However, under 90° polarization, due to enhanced light absorption, more photogenerated carriers are generated in the (BP / hBN)-(BP / SiO2) homojunction detector, leading to an increase in the number of bound photogenerated electrons. At this point, the p-type doping degree of BP on SiO2 is increased again, and the Fermi level is significantly reduced. The result of this process is that, under continuous illumination, as the incident light polarization angle increases,

[0107] The built-in electric field strength of the (BP / hBN)-(BP / SiO2) homojunction gradually decreases. Overall, the p-type doping degree of p-doped BP wafers obtained by mechanical exfoliation first decreases and then increases when they are placed in a light environment after being exposed to SiO2 in the dark.

[0108] like Figure 7 As shown, by applying a positive local gate voltage at the BP / hBN interface ( V g ), BP / hBN region E f The doping level will increase again, while the p-type doping level will decrease, and the BP / SiO2 region will... E f The changes are minor. For example... Figure 8 As shown, when both of them E f When they are equal, the (BP / hBN)-(BP / SiO2) homojunction disappears, and the self-driven photoresponse also decreases to zero. This specific V g The value is called the flat band grid voltage ( V g-FB ).

[0109] like Figure 9 As shown, with V gAs the beam increases further, the (BP / hBN)-(BP / SiO2) homojunction will reverse, thus generating a reverse self-driven photocurrent. Because the band modulation caused by optical gating is polarization-dependent, this photocurrent polarity reversal occurs at different polarization states of the incident light. V g Value location. For example... Figure 10 As shown, with an incident light wavelength of 3.3 μm and a power density of 45 mW / cm², -2 Under certain conditions, the photocurrent polarity reversal of 90° polarized light occurs V g = 3.85 V, while the polarity reversal of 0° polarized light occurs V g = 5.2 V.

[0110] The polarization extinction ratio (PER) is defined as follows: I 90° / I 0° The scope of application is | I 90° |>| I 0° |, otherwise it is defined as I 0° / I 90° By adjusting V g PER can be configured to all possible values ​​within the range (1 → ∞ / -∞ → -1). V g = 3.85V corresponds to the photocurrent polarity reversal point of 90° polarized light. I 90° = 0 nA, while I 0° = -1.8 nA, resulting in PER = ∞ / -∞. At the polarity reversal point of 0° polarized light, i.e. V g = 5.2 V, I 90° = 105 nA, while I 0° = 0 nA, which also results in PER = ∞ / -∞. In V g Between 3.85 V and 5.2 V, the PER value turns negative. The result of PER = ∞ / -∞ indicates that the (BP / hBN)-(BP / SiO2) homojunction detector has extremely high discrimination capability for the polarization state of the incident light.

[0111] Figure 11The (BP / hBN)-(BP / SiO2) homojunction detector was demonstrated under different optical power density irradiation. I ds - V ds Characteristics. The presence of short-circuit current and open-circuit voltage indicates that its self-driven photoresponse mechanism originates from the photovoltaic effect, thus confirming the existence of the (BP / hBN)-(BP / SiO2) homojunction. When a bias voltage is applied to the (BP / hBN)-(BP / SiO2) homojunction detector, the photoresponse arises from the combined effect of the photovoltaic and photoconductive effects. The lack of observed rectification effect may be due to the high carrier concentration of the BP.

[0112] Figure 12 This demonstrates the photocurrent variation of the (BP / hBN)-(BP / SiO2) homojunction detector at different polarization angles. V g The situation is changing. With... V g As the photocurrent gradually increases, the polarity of the photocurrent in the (BP / hBN)-(BP / SiO2) homojunction detector reverses. I ph = 0 nA (i.e., the corresponding flat-band gate voltage is) V g-FB The disappearance of the (BP / hBN)-(BP / SiO2) homojunction causes the self-driven photoresponse to return to zero. It is worth noting that under different incident polarization angles, V g-FB The corresponding gate voltage values ​​differ. At a wavelength of 3.3 μm and a power density of 65 mW / cm², the values ​​are different. -2 Under incident light illumination, as the polarization angle increases from 0° to 90°, V g-FB The voltage dropped from 5.3V to 3.65V. This phenomenon can be attributed to the increased light absorption rate of BP with increasing polarization angle, resulting in more photogenerated electrons being trapped at the BP / SiO2 interface. This weakens the positive grating effect generated by the bound intrinsic majority carriers in BP at the BP / SiO2 interface, thus reducing the voltage at the BP / SiO2 interface. E f Reduced. Based on this anisotropic optical gating effect, the zero photocurrent state of the (BP / hBN)-(BP / SiO2) homojunction detector can be set at any polarization angle, thereby effectively suppressing background radiation interference under a specific polarization state.

[0113] exist V g At 5.3 V, the photocurrent measurement results show that... I 90° = 138 nA, while I0° = 0 nA,

[0114] This indicates that the (BP / hBN)-(BP / SiO2) homojunction detector has extremely high selectivity for 90° polarized light, with a PER reaching ∞ / -∞. Figure 13 Further demonstration V g The polarization-dependent photocurrent curves at 0 V and 5.3 V are shown. Experimental results indicate that after applying a local gate voltage of 5.3 V, I 0° The decrease from -6.5 nA to 0 nA significantly improved the PER from 17.2 to ∞ / -∞. Similarly, in V g = 3.65 V, I 0° = -1.9 nA, while I 90° = 0 nA indicates that the (BP / hBN)-(BP / SiO2) homojunction detector has extremely high selectivity for 0° polarized light under this condition, and PER also reaches ∞ / -∞.

[0115] Because anisotropic optical gating is not limited to a specific wavelength, (BP / hBN)-(BP / SiO2) homojunction detectors can achieve ultra-high resolution polarization detection over a wide wavelength range. When the incident light wavelength is 2.2 µm and the power density is 357 mW / cm², this is achievable. -2 At times, such as Figure 14 As shown, as the local gate voltage is adjusted from 0 V to 5.2 V, the PER can be significantly increased from 5.14 to ∞ / -∞. This is achieved when the incident light wavelength is 1.55 µm and the power density is 2.9 mW / cm². -2 At times, such as Figure 15 As shown, when V g Increasing from 0 V to 4.5 V, PER can be singularly boosted from 3.38 to ∞ / -∞. Therefore, by... V g Set as V g-FB (90°) or V g-FB (0°), (BP / hBN)-(BP / SiO2) homojunction devices can achieve ultra-high resolution infrared polarization detection in different wavelength ranges.

[0116] When the polarization state of the incident light is in a specific direction, the (BP / hBN)-(BP / SiO2) homojunction detector enters the flat band condition. At this time, the (BP / hBN)-(BP / SiO2) homojunction disappears, causing the photoelectric response to return to zero.

[0117] Under flat-band conditions, the (BP / hBN)-(BP / SiO2) homojunction detector not only exhibits zero optical response but also significantly reduced noise. In the experiment, the wavelength of the incident light was fixed at 3.3 μm, and the optical power density was 65 mW / cm². -2 Local gate voltage is V g-FB (0°) = 5.3 V. As the polarization angle gradually changes from 90° to 0°, the noise level of the (BP / hBN)-(BP / SiO2) homojunction detector decreases by 1 to 2 orders of magnitude (e.g., Figure 16 (As shown). At a polarization direction of 0°, a photoelectric quiescent state occurs, and the noise of the (BP / hBN)-(BP / SiO2) homojunction detector reaches a minimum, approaching the level of dark noise. This reconfigurable polarization-dependent photoelectric quiescent state effectively suppresses infrared background noise, making targets with different polarization states stand out more. By optimizing the local gate voltage setting, the photoelectric response caused by background radiation can be selectively eliminated in any polarization state, significantly reducing background noise and thus significantly enhancing the contrast between the target and the background.

[0118] PER and V g The relationship between them is as follows Figure 17 As shown. The background color changing from blue to red represents PER changing from positive to negative. When... V g < V g-FB At (90°), PER is positive; while when V g > V g-FB At (90°), PER becomes negative. In contrast, at... V g < V g-FB At (0°), PER is negative, while... V g > V g-FB At (0°), PER turns positive. Therefore, in V g-FB (0°) and V g-FB Near (90°), PER can reach ∞ or -∞.

[0119] The photoelectric response characteristics under blackbody radiation are an important indicator for evaluating the practical application capabilities of infrared detectors. Compared to laser sources, blackbody radiation has a wider spectral distribution, but its intensity is weaker, and its radiation power decreases further with decreasing blackbody temperature. Therefore, most infrared detectors based on two-dimensional van der Waals materials are difficult to characterize using blackbody sources. However, the (BP / hBN)-(BP / SiO2) homojunction detector not only possesses ultra-high polarization resolution but also responds sensitively to blackbody radiation, marking a significant breakthrough in the practical application of two-dimensional polarization detectors.

[0120] Figure 18 The responsivity and specific detectivity of the (BP / hBN)-(BP / SiO2) homojunction detector at different blackbody temperatures are presented. The test results show that the (BP / hBN)-(BP / SiO2) homojunction can respond to blackbody temperatures as low as 468 K. With increasing blackbody temperature, both the responsivity and specific detectivity significantly improve, reaching 0.104 AW at 1268 K (the experimental upper limit). -1 and 7.6 × 10 8 cm Hz 1 / 2 W -1 This result demonstrates that (BP / hBN)-(BP / SiO2) homojunction detectors have broad application potential in fields such as infrared imaging and thermal radiation detection.

[0121] For blackbody radiation signals with polarization characteristics, the (BP / hBN)-(BP / SiO2) homojunction detector can also achieve ultra-high polarization resolution of ∞ / -∞ PER.

[0122] like Figure 19 As shown, the photoelectric quiescent state of the (BP / hBN)-(BP / SiO2) homojunction detector corresponds to different polarization angles. V g-FB It appears at different local gate voltage values. For polarized blackbody radiation at 1268K, its V g-FB (0°) is 4.06 V. At this point, the photocurrent corresponding to 0° polarization is zero, while the photocurrent corresponding to 90° polarization is very significant, causing PER to approach ∞ / -∞. For example... Figure 20 As shown, when V g When the voltage is adjusted from 0 V to 4.06 V, the per ion ratio (PER) of the (BP / hBN)-(BP / SiO2) homojunction under blackbody radiation increases from 16.9 to ∞ / -∞.

[0123] Although the (BP / hBN)-(BP / SiO2) homojunction detector relies on optical gating, it still exhibits an astonishingly fast optical response speed. For example... Figure 21 As shown, the rise and fall times of the (BP / hBN)-(BP / SiO2) homojunction detector are 4.4 μs and 4.3 μs, respectively. In contrast, the photoresponse time of conventional phototransistors based on the optical gating effect typically exceeds several seconds. This significant difference stems from the fact that conventional phototransistors utilize the optical gating effect to modulate the channel conductance, while the (BP / hBN)-(BP / SiO2) homojunction detector utilizes the optical gating effect to modulate the band structure of the homojunction.

[0124] In traditional devices, changes in photocurrent are directly affected by channel conductivity modulation.

[0125] In the (BP / hBN)-(BP / SiO2) homojunction structure, the generation of photocurrent does not depend on the modulation of the conductive channel, but is controlled by the built-in electric field generated by band bending. As the incident light modulation frequency increases, the modulation speed of the channel conductivity and the band distribution become increasingly difficult to keep up with the light modulation speed. Even under modulated illumination, the band distribution of the homojunction remains unchanged. However, as long as the built-in electric field exists, the photocurrent can be continuously generated. The photoresponse speed depends on the homojunction's own characteristics, such as junction capacitance and the generation-recombination probability of photogenerated carriers. When the incident light modulation frequency is high, the band distribution of the (BP / hBN)-(BP / SiO2) homojunction cannot keep up with the illumination changes in time; therefore, the built-in electric field remains constant and is determined by the average optical power. Although the band distribution remains unchanged, the photoresponse can still be generated stably, and the photoresponse speed can still keep up with the modulation speed changes of incident light below 80 kHz.

[0126] Example 2

[0127] This invention provides a fabrication process for an infrared polarization detector based on anisotropic optical gating, used to fabricate the infrared polarization detector of this invention. Taking the fabrication of the (BP / hBN)-(BP / SiO2) homojunction detector described in Example 1 as an example, the fabrication process includes:

[0128] The bottom substrate (single-polished double oxide SiO2 / Si substrate, SiO2 thickness 285 nm, Si thickness 500 μm, so the thickness h0 of the bottom substrate is about 500 μm) was sequentially placed in acetone, isopropanol, and deionized water and sonicated for 10 minutes, and then the surface was dried with nitrogen.

[0129] The pattern of the local gate layer is defined on the bottom substrate layer by three steps: coating, photolithography and development using ultraviolet lithography. A 3 nm Ti and a 27 nm Au film are deposited sequentially using electron beam evaporation or thermal evaporation. The thickness of Ti is 1 / 9 of that of Au. The deposited sample is then placed in acetone for peeling to complete the preparation of the bottom substrate layer with the local gate layer.

[0130] A thin layer of hBN was obtained from a single-crystal hBN sample using mechanical exfoliation as the dielectric layer, and then transferred onto the local gate layer using a dry transfer technique. The general process of dry transfer involves transferring the mechanically exfoliated dielectric layer onto the local gate layer using polycarbonate (PC) and polydimethylsiloxane (PDMS). Residual polycarbonate (PC) is removed using a chloroform solution. Alternatively, the dielectric layer can be obtained directly using atomic layer deposition (ALD), and its pattern can be defined using ion beam etching.

[0131] Using ultraviolet lithography, after the local gate layer and dielectric layer are prepared, the source electrode layer and drain electrode layer are patterned by three steps: coating, photolithography and development. Electron beam evaporation or thermal evaporation is used to deposit 3 nm Ti and 27 nm Au in sequence for film deposition. Then, the deposited sample is placed in acetone for peeling to obtain the source electrode layer and drain electrode layer.

[0132] A thin layer of black phosphorus was obtained from a single-crystal black phosphorus sample using a mechanical exfoliation method as a two-dimensional material layer, and the black phosphorus was transferred onto the source electrode layer and the drain electrode layer using a dry transfer technique.

[0133] Local gate layer: Ti: 3 nm, Au: 27 nm, so h1 is 30 nm, width d1: 15 μm.

[0134] Dielectric layer material: hBN, width d2: 18 μm, thickness h2: 53 nm.

[0135] Thickness of source and drain electrode layers: Ti: 3 nm, Au: 27 nm, channel width d3: 30 nm.

[0136] Two-dimensional material layer: The material is black phosphorus, with a thickness of 39 nm.

[0137] The above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating, characterized in that, It includes a bottom substrate layer (1), a local gate layer (2), a dielectric layer (3), a source electrode layer (4-1), a drain electrode layer (4-2), and a two-dimensional material layer (5); the local gate layer (2) is disposed above the bottom substrate layer (1); the dielectric layer (3) is disposed above the local gate layer (2); the source electrode layer (4-1) or the drain electrode layer (4-2) is disposed above the dielectric layer (3), and the other electrode layer of the source electrode layer (4-1) or the drain electrode layer (4-2) is disposed above the bottom substrate layer (1); A two-dimensional material layer (5) is disposed above the source electrode layer (4-1) and the drain electrode layer (4-2), and the two-dimensional material layer (5) is connected to the source electrode layer (4-1) and the drain electrode layer (4-2) respectively; or, the two-dimensional material layer (5) is disposed above the dielectric layer (3) and the bottom substrate layer (1), and the source electrode layer (4-1) and the drain electrode layer (4-2) are disposed above the two-dimensional material layer (5); The number of bound states of the dielectric layer (3) material is different from that of the bottom substrate layer (1) material; the two-dimensional material layer (5) is an anisotropic material; a part of the two-dimensional material layer (5) is in contact with the bottom substrate layer (1), and the other part is in contact with the dielectric layer (3); The local gate layer (2) is a conductive material with a thickness of h1; the local gate layer (2) has a width d1 in the horizontal direction; The dielectric layer (3) has a width d2 in the horizontal direction, which is 0-10 μm wider than the width d1 of the local gate layer (2). The centers of the dielectric layer (3) and the local gate layer (2) coincide in the horizontal direction. The two-dimensional material layer is BP material, the dielectric material is hBN, and the bottom substrate layer is SiO2. The two-dimensional material layer BP has two contact interfaces in the horizontal direction: one side is the bottom substrate layer SiO2 containing bound states, and the other side is the dielectric layer material hBN with almost no bound states, forming a (BP / hBN)-(BP / SiO2) homojunction.

2. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 1, characterized in that: The bottom substrate layer (1) is a support layer with a thickness of h0.

3. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 1, characterized in that, The range of h1 is 1-100 nm; the range of d1 is 5-20 μm.

4. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 1, characterized in that: The local gate layer (2) is made of materials including but not limited to metallic materials such as gold, silver, aluminum and their alloys, or graphene.

5. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 3, characterized in that: The dielectric layer (3) is a dielectric material with a thickness of h2 and is non-conductive; the range of h2 is 10-100 nm.

6. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 1, characterized in that: The source electrode layer (4-1) and drain electrode layer (4-2) are made of metallic materials.

7. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 1, characterized in that: In the (BP / hBN)-(BP / SiO2) homojunction, BP / hBN and BP / SiO2 form in-plane PP at the interface. - Homojunction.

8. The ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating control according to claim 3, characterized in that: In the source electrode layer (4-1) and the drain electrode layer (4-2), the channel width between the two electrode regions of the source electrode layer (4-1) and the drain electrode layer (4-2) is d3. The channel width d3 is greater than the width d1 of the local gate layer (2). The range of d3 is 20-100 μm.

9. A fabrication process for an infrared polarization detector based on anisotropic optical gating, characterized in that, The process for fabricating the ultra-high extinction ratio infrared polarization detector based on anisotropic optical gating manipulation as described in any one of claims 1-8 includes: After immersing the bottom substrate layer in acetone, isopropanol, and deionized water and sonicating for a certain period of time, the surface is dried with nitrogen. The pattern of the local gate layer is defined on the bottom substrate using ultraviolet lithography through three steps: coating, photolithography, and development. Metals Ti and Au are deposited sequentially using electron beam evaporation or thermal evaporation to form a film. The coated sample is then placed in acetone for peeling to obtain the local gate layer. The dielectric layer is obtained from the single crystal dielectric material using mechanical stripping and transferred onto the local gate layer using dry transfer technology. Alternatively, the dielectric layer can be obtained directly using atomic layer deposition and the pattern of the dielectric layer can be defined using ion beam etching. The source electrode layer and drain electrode layer are patterned on the bottom substrate layer after the local gate layer and dielectric layer are prepared by ultraviolet lithography through three steps: coating, photolithography and development. Metal Ti and Au are deposited sequentially by electron beam evaporation or thermal evaporation to form a film. Then the coated sample is placed in acetone for peeling to obtain the source electrode layer and drain electrode layer. Two-dimensional material layers were obtained from single-crystal two-dimensional material samples using mechanical exfoliation, and then transferred onto the source electrode layer and drain electrode layer using dry transfer technology.

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