Metastructure surface absorber for enhancing narrow-band absorption efficiency of ultraviolet photoelectric material

Abstract

The invention discloses a super-structure surface absorber for enhancing narrow-band absorption efficiency of an ultraviolet photoelectric material, and relates to the field of ultraviolet detection. The super-structure surface absorber comprises a substrate layer, a medium absorption layer and a medium resonance layer which are sequentially arranged from bottom to top, the dielectric absorption layer is used as an absorption layer and a photoelectric conversion material; the material of the medium absorption layer meets the condition that a refractive index imaginary part is not zero in an ultraviolet target spectrum band; the dielectric resonance layer is an array formed by periodically arranging sub-wavelength micro-nano structures; the dielectric resonance layer is used for exciting a narrow-band optical resonance mode of a high-quality factor and enhancing the absorption intensity of the dielectric absorption layer; the central wavelength and intensity of absorption are adjusted by adjusting the size and period of the micro-nano structure in the dielectric resonance layer. The absorption strength of the ultraviolet photoelectric material can be enhanced.

Description

Technical Field

[0001] The present invention relates to the field of ultraviolet detection, and in particular to a metasurface absorber for enhancing the narrow-band absorption efficiency of ultraviolet photoelectric materials. Background Art

[0002] The efficient detection of ultraviolet light (UV, 200-400nm) has important application value in the fields of space detection, low-altitude monitoring, biomedical sensing, etc. Among them, in applications such as fluorescence detection, it is necessary to accurately detect ultraviolet light in a specific spectral band, which requires ultraviolet photodetectors to have a narrow-band response curve with high spectral selectivity. The core and premise of detection is efficient absorption. The absorption efficiency and detection bandwidth of photoelectric materials are determined by factors such as the band gap and composition of the materials. Therefore, the response performance of detectors in the ultraviolet band is limited by factors such as the type of material and the preparation process. For semiconductor materials such as gallium oxide, their response bandwidth and central wavelength need to be controlled by optimizing the material composition and preparation process. It is very difficult to achieve narrow-band absorption with controllable response wavelength, and it is often necessary to place a filter or other spectroscopic element in front of the detector to achieve it. However, due to material limitations, film system design and other reasons, the transmission efficiency of some narrow-band filters with specific ultraviolet frequencies is only 10%. The extremely low energy utilization efficiency seriously affects the responsiveness and signal-to-noise ratio of ultraviolet narrow-band detection. Therefore, exploring efficient ultraviolet narrow-band absorption solutions without filters is of great significance to improving the performance of ultraviolet spectral detection devices. Summary of the invention

[0003] The purpose of the present invention is to provide a metasurface absorber that enhances the narrowband absorption efficiency of ultraviolet photoelectric materials, and can enhance the absorption intensity of ultraviolet photoelectric materials.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A metasurface absorber for enhancing the narrowband absorption efficiency of ultraviolet photoelectric materials, the metasurface absorber comprising a substrate layer, a dielectric absorption layer and a dielectric resonance layer arranged in sequence from bottom to top;

[0006] The dielectric absorption layer serves as an absorption layer and a photoelectric conversion material; the material of the dielectric absorption layer satisfies that the imaginary part of the refractive index is not zero in the ultraviolet target spectrum;

[0007] The dielectric resonance layer is an array of periodically arranged sub-wavelength micro-nano structures; the dielectric resonance layer is used to excite a narrow-band optical resonance mode with a high quality factor and enhance the absorption intensity of the dielectric absorption layer; the central wavelength and intensity of the absorption are adjusted by adjusting the size and period of the micro-nano structures in the dielectric resonance layer.

[0008] Optionally, the material of the dielectric absorption layer is an ultraviolet semiconductor photoelectric material.

[0009] Optionally, the material of the dielectric absorption layer includes gallium oxide, gallium nitride, silicon, diamond, zinc oxide, tin oxide and silicon carbide.

[0010] Optionally, the dielectric absorption layer has a thickness ranging from 20 nanometers to 100 nanometers.

[0011] Optionally, the material of the substrate layer includes quartz, sapphire and ITO.

[0012] Optionally, the thickness of the substrate layer ranges from 200 microns to 1000 microns.

[0013] Optionally, the material of the dielectric resonance layer includes silicon dioxide, aluminum oxide, aluminum nitride and hafnium oxide;

[0014] Optionally, the thickness of the dielectric resonance layer ranges from 100 nanometers to 1000 nanometers.

[0015] Optionally, the cross-section of the micro-nano structure includes a circle, a rectangle and a triangle.

[0016] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0017] The present invention discloses a metasurface absorber for enhancing the narrowband absorption efficiency of ultraviolet optoelectronic materials, including a substrate layer, a dielectric loss layer, and a dielectric resonance layer. By controlling the optical resonance absorption mode of the high quality factor induced by the metasurface in the dielectric resonance layer, it acts on the ultraviolet optoelectronic material in the dielectric loss layer to achieve efficient narrowband absorption enhancement in a specific band. The solution provided by the present invention solves the problems of low absorption spectrum resolution of optoelectronic materials and difficulty in achieving absorption center wavelength control in ultraviolet narrowband detection, overcomes the dependence on narrowband filters in ultraviolet narrowband detection, and avoids energy loss caused by spectroscopy. The structural design of the metasurface can achieve precise control of the absorption wavelength, and it is easy to realize the integration of multi-wavelength detectors. The present invention can simplify the ultraviolet narrowband detection optical system, which is conducive to integrated large-scale manufacturing and cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of Example 1 of the metasurface absorber for enhancing the narrowband absorption efficiency of ultraviolet optoelectronic materials according to the present invention;

[0020] Figure 2 is a schematic diagram of the unit structure of Example 1 of the present invention;

[0021] Figure 3 is the absorption spectrum of Example 1 of the present invention;

[0022] Figure 4 These are multiple absorption spectra obtained by adjusting the structural parameters in Example 1 of the present invention.

[0023] Description of reference numerals:

[0024] Substrate layer—1, dielectric absorption layer—2, dielectric resonance layer—3. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The purpose of the present invention is to provide a metasurface absorber that enhances the narrowband absorption efficiency of ultraviolet optoelectronic materials, aiming to enhance the absorption intensity of ultraviolet optoelectronic materials.

[0027] The design of detection devices integrated with metasurfaces provides a new feasible solution for enhancing the performance of ultraviolet detectors. The generation and coupling of optical resonance modes can be regulated by designing the structure, size, and arrangement of micro-nano structures in metasurfaces. Metasurfaces can achieve efficient capture of incident light by reducing light reflectivity through light trapping effects, and can achieve optical resonance-driven absorption enhancement by increasing the intensity of light-matter interaction through highly localized light fields. The absorption capacity of materials is no longer determined by their own extinction coefficient and film thickness, which provides a new paradigm for improving the absorption efficiency of detectors. Therefore, it is a feasible solution to achieve ultraviolet narrow-band detection with controllable wavelength and bandwidth to select modes through metasurfaces, screen narrow-band resonant absorption modes with high quality factors, and apply them to optoelectronic materials for ultraviolet detection.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] like Figure 1 As shown, the metasurface absorber for enhancing the narrowband absorption efficiency of ultraviolet optoelectronic materials in this embodiment includes a substrate layer 1, a dielectric absorption layer 2 and a dielectric resonance layer 3 arranged in sequence from bottom to top.

[0031] The dielectric absorption layer 2 serves as an absorption layer and a photoelectric conversion material. The material of the dielectric absorption layer 2 satisfies that the imaginary part of the refractive index is not zero in the ultraviolet target spectrum.

[0032] The dielectric resonance layer 3 is an array of periodically arranged sub-wavelength micro-nano structures. The dielectric resonance layer 3 is used to excite a narrow-band optical resonance mode with a high quality factor and enhance the absorption intensity of the dielectric absorption layer 2. The central wavelength and intensity of the absorption are adjusted by adjusting the size and period of the micro-nano structures in the dielectric resonance layer 3.

[0033] Specifically, the metasurface absorber is a three-layer structure, including: a substrate layer 1, a dielectric absorption layer 2, and a dielectric resonance layer 3. The dielectric absorption layer 2 is arranged on the substrate layer 1, and the dielectric resonance layer 3 is arranged on the dielectric absorption layer 2.

[0034] The substrate layer 1 is a supporting layer of the device, and the optional materials are low-loss ultraviolet materials such as quartz, sapphire and ITO. In this embodiment, it is set to quartz. The substrate layer 1 plays a structural support role and participates in the excitation of the optical resonance mode as a low-loss optical material. Insulating or conductive materials can be selected according to the type of ultraviolet detector and its specific structural requirements, and the preferred thickness is 200 to 1000 microns.

[0035] The dielectric absorption layer 2 uses a material whose imaginary part of the refractive index, i.e., the loss rate, is not zero in the ultraviolet target spectrum, and has a certain intrinsic absorption effect, and serves as an absorption layer and a photoelectric conversion material. The dielectric resonance layer 3 is an array of periodically arranged sub-wavelength micro-nano structures, and serves as an optical resonance layer to excite a narrow-band optical resonance mode with a high quality factor, acting on the dielectric absorption layer 2 to enhance its absorption intensity. The central wavelength and intensity of the absorption can be adjusted by controlling the size, period, and other parameters of the micro-nano structures in the optical resonance layer.

[0036] The dielectric absorption layer 2 is an optical loss layer of the device, which has an absorption function, and realizes photoelectric conversion by absorbing ultraviolet light to generate carriers to realize ultraviolet detection. Ultraviolet semiconductor photoelectric materials such as gallium oxide, gallium nitride, silicon, diamond, zinc oxide, tin oxide and silicon carbide can be used, and the thickness is preferably 20 to 100 nanometers. In this embodiment, it is set to gallium oxide. The dielectric absorption layer 2 is an optical film, which can be prepared by magnetron sputtering, molecular beam epitaxy, high-temperature evaporation, etc.

[0037] The dielectric resonance layer 3 is composed of a subwavelength metasurface, which induces high quality factor resonance on the dielectric absorption layer 2 to achieve efficient narrowband absorption. The dielectric resonance layer 3 is an optical resonance layer, which includes a plurality of periodic dielectric resonator arrays. It should be set to a low-loss material to limit the absorption intensity of light in the resonator. Low-loss ultraviolet materials such as silicon dioxide, aluminum oxide, aluminum nitride and hafnium oxide can be used. The use of high refractive index materials is more conducive to the excitation and control of optical modes. In this embodiment, the material of the dielectric resonance layer 3 is set to aluminum oxide, and the preferred thickness is 100 to 1000 nanometers. The dielectric resonance layer 3 is a micro-nano structure array, which can be processed into a circular, rectangular, triangular and other geometric structure or a microstructure array of a pattern obtained by a combination of several of them through micro-nano processing technology.

[0038] By designing the periodic micro-nanostructure array of the dielectric resonant layer 3, the generation of high-quality factor optical resonance modes can be induced, the light energy of a specific frequency can be confined within the structure, the interaction between light and matter can be enhanced, and then act on the dielectric absorption layer 2 to achieve high-efficiency narrowband absorption. The absorption effect in the multilayer stacking system can be analyzed by the coupled mode theory. When there are two or more resonant modes in the system, the superposition of different electromagnetic modes can be regarded as the superposition of coupling effects between different coupling cavities. Considering two weakly coupled resonant cavities, it can be expressed as:

[0039]

[0040] Among them, a i is the amplitude of resonant cavity i, ω i is the resonant frequency of cavity i, β i is the coupling coefficient between the resonant cavity i and free space, S +i is the incident wave amplitude of the resonant cavity i, κ is the mutual coupling coefficient between the two resonant cavities, i = 1, 2. Further, when the resonant frequency satisfies ω0 = ω1 = ω2, and the coupling coefficient satisfies β = β1 = β2, where ω0 is the resonant frequency and β is the coupling coefficient between the resonant cavity and the free space, the absorptivity A of the metasurface absorber can be expressed as:

[0041]

[0042] It can be seen from the expression of the absorption rate A that at the resonant frequency (ω=ω0), if β=κ, perfect absorption occurs, which requires that the coupling between the two resonant cavities matches the coupling between the resonant cavity and the free space, that is, the coupling between the optical electromagnetic resonance modes, which is usually achieved by setting the parameters of the resonator array in the metasurface (including the shape, size and period of the micro-nanostructure, etc.). Specifically, the intensity and resonant wavelength of the electromagnetic resonance mode are controlled by changing the geometric parameters such as the shape, size, spacing, and height of the micro-nanostructure in the micro-nanostructure array. Because different electromagnetic modes have different sensitivities to changes in these parameters, the parameters are adjusted to overlap the response spectra of the two resonant absorption modes. In order to better control the radiation loss and the inherent loss of the material, the resonator should be set to a lossless or low-loss optical material so that the energy dissipation and the photoelectric conversion effect occur completely in the dielectric absorption layer 2, and the absorption enhancement of the ultraviolet photoelectric material is achieved. Furthermore, by exciting optical resonance modes with high quality factors such as guided mode resonance and bound state effect in the continuous state, the spectrum range where efficient absorption enhancement occurs is limited to achieve narrow-band efficient absorption.

[0043] like Figure 2 As shown, the structural dimension parameters of the superstructure unit of Example 1 are as follows: the unit interval g of the dielectric resonance layer is 45 nanometers, the diameter R of the nanocolumn is 200 nanometers, the height H1 is 114 nanometers, and the thickness H2 of the dielectric loss layer is 20 nanometers.

[0044] like Figure 3 As shown in the figure, a narrow-band absorption peak with an absorptivity of 95.0% is obtained at a wavelength of 355 nanometers, with a full width at half maximum (FWHM) of 1.54 nanometers and an absorption quality factor (Q) of 230, achieving efficient narrow-band absorption enhancement. It should be noted that the quality factor is obtained according to the calculation formula Q = λ / FWHM, where Q is the quality factor and λ is the wavelength of light. Compared with the spectrum bands without resonant absorption enhancement at wavelengths of 350 nanometers and 360 nanometers, the absorptivity is increased by 20 times, with better spectral absorption resolution.

[0045] One of the advantages of the narrow-band absorption effect achieved based on the metasurface absorber in the present invention is that the absorption wavelength can be changed by adjusting the geometric parameters of the micro-nano structure in the dielectric resonance layer 3. Figure 4 Figure 4 shows multiple narrow-band absorption spectra obtained by adjusting the spacing and diameter of the nanorod units. Figure 4 As shown, the central wavelength of the absorption peak changes uniformly from 345 nanometers to 380 nanometers at 5 nanometer intervals, the absorption rate remains above 90%, and the FWHM is less than 2 nanometers. It should be noted that during the change of nanocolumn parameters, the height of the nanocolumn remains consistent, so as to simplify the micro-nano processing process and the integration of multi-wavelength detectors.

[0046] The metasurface absorber provided by the present invention can enhance the narrowband absorption efficiency of ultraviolet photoelectric materials, overcome the reliance of existing ultraviolet detectors on narrowband filters, and solve the problems of low resolution of the absorption spectrum of photoelectric materials and difficulty in controlling the absorption center wavelength in ultraviolet narrowband detection. The optical resonance absorption mode with high quality factor induced by the metasurface can achieve efficient narrowband absorption in a specific band, and the absorption wavelength can be adjusted by changing the geometric characteristics of the dielectric resonator. The scheme for enhancing the narrowband absorption of ultraviolet photoelectric materials provided by the present invention overcomes the reliance on ultraviolet narrowband filters, avoids energy loss caused by spectroscopy, easily realizes the integration of multi-wavelength detectors, simplifies the structural design of the ultraviolet photoelectric detection system, and is conducive to integrated large-scale manufacturing and cost reduction.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. By using a low-loss dielectric metasurface to excite a high-quality factor strong optical resonance mode, the absorption intensity of a specific ultraviolet optoelectronic material is enhanced, so that the device has an efficient and wavelength-adjustable narrow-band absorption spectrum curve, realizing the functional integration of spectroscopy and detection. This overcomes the limitations of spectroscopy components such as ultraviolet narrow-band filters and avoids energy loss caused by spectroscopy.

[0049] 2. The present invention does not adopt the metal metasurface, metal nanowires or the scheme of introducing a metal reflective layer commonly used in the field, which effectively avoids the Ohmic loss effect of the metal. Through reasonable material selection, the ultraviolet absorption occurs completely in the functional material specified by the dielectric loss layer. The intensity of the interaction between light and matter is improved by the metasurface, while avoiding the energy loss caused by the high-gain local field.

[0050] 3. In order to improve the absorption intensity, the thickness of the optical absorption layer in traditional ultraviolet detectors is usually above 200 nanometers. The metasurface absorber described in the present invention can reduce the thickness of the absorption layer to 20 nanometers. Under the premise of ensuring the absorption efficiency, the extremely small film thickness is conducive to improving the carrier recombination rate of the detector and improving the response speed.

[0051] 4. As a planar optical element, the introduction of metasurface devices can greatly simplify the structure of the ultraviolet spectrum detection system while achieving efficient ultraviolet detection, which is conducive to integrated large-scale manufacturing, thereby reducing manufacturing costs.

[0052] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A metasurface absorber for enhancing the narrowband absorption efficiency of ultraviolet optoelectronic materials, characterized in that: The metasurface absorber comprises a substrate layer, a dielectric absorption layer and a dielectric resonance layer arranged in sequence from bottom to top; The dielectric absorption layer serves as an absorption layer and a photoelectric conversion material; the material of the dielectric absorption layer satisfies that the imaginary part of the refractive index is not zero in the ultraviolet target spectrum; The dielectric resonance layer is an array of sub-wavelength micro-nano structures arranged periodically; The dielectric resonance layer is used to excite a narrowband optical resonance mode with a high quality factor and enhance the absorption intensity of the dielectric absorption layer; the central wavelength and intensity of the absorption are adjusted by adjusting the size and period of the micro-nano structure in the dielectric resonance layer.

2. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The material of the dielectric absorption layer is ultraviolet semiconductor photoelectric material.

3. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The material of the dielectric absorption layer includes gallium oxide, gallium nitride, silicon, diamond, zinc oxide, tin oxide and silicon carbide.

4. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The thickness of the dielectric absorption layer ranges from 20 nanometers to 100 nanometers.

5. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The material of the substrate layer includes quartz, sapphire and ITO.

6. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The thickness of the substrate layer ranges from 200 micrometers to 1000 micrometers.

7. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The material of the dielectric resonance layer includes silicon dioxide, aluminum oxide, aluminum nitride and hafnium oxide.

8. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The thickness of the dielectric resonance layer ranges from 100 nanometers to 1000 nanometers.

9. The metasurface absorber for enhancing narrowband absorption efficiency of ultraviolet optoelectronic materials according to claim 1, characterized in that: The cross-section of the micro-nano structure has a shape including a circle, a rectangle and a triangle.

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