阅读说明：本技术 一种提高折射率传感器件品质因数的结构及测试方法 (Structure for improving quality factor of refractive index sensing device and testing method ) 是由 黄小丹 仇超 王诗军 季小峰 王艳 朱敏 于 2020-07-15 设计创作，主要内容包括：本发明涉及一种提高折射率传感器件品质因数的结构及测试方法,属于传感器折射率品质因数的领域。该结构由基底、位于基底表面的复合层组成,所述复合层包括上金属层、中间半导体层和下介电层,其中上金属层为周期性的金属纳米颗粒阵列,中间半导体层为周期性的半导体纳米柱阵列,下介电层为周期性的介电纳米柱阵列。利用本发明中金属纳米颗粒的局域表面等离激元共振、半导体纳米柱的米氏共振与周期阵列的衍射波之间的多元耦合作用,以及介电纳米柱减弱的衬底效应,能获得灵敏度较高、带宽极窄的等离激元晶格共振,克服了传统金属等离激元晶格共振结构存在带宽较宽的问题,提高了折射率传感器件的品质因数,在生物、医学、食品等领域具有广泛应用。(The invention relates to a structure for improving the quality factor of a refractive index sensing device and a test method, belonging to the field of the quality factor of the refractive index of a sensor. The structure consists of a substrate and a composite layer positioned on the surface of the substrate, wherein the composite layer comprises an upper metal layer, a middle semiconductor layer and a lower dielectric layer, the upper metal layer is a periodic metal nanoparticle array, the middle semiconductor layer is a periodic semiconductor nanorod array, and the lower dielectric layer is a periodic dielectric nanorod array. By utilizing the multi-coupling effect between the local surface plasmon resonance of the metal nano particles, the Mie resonance of the semiconductor nano columns and the diffraction waves of the periodic array and the substrate effect weakened by the dielectric nano columns, the plasmon lattice resonance with higher sensitivity and extremely narrow bandwidth can be obtained, the problem of wider bandwidth of the traditional metal plasmon lattice resonance structure is solved, the quality factor of the refractive index sensing device is improved, and the method has wide application in the fields of biology, medicine, food and the like.)

1. The structure for improving the quality factor of the refractive index sensing device is characterized by comprising a substrate (4) and a plurality of composite layers arranged in an array mode and positioned on the surface of the substrate (4), wherein each composite layer comprises a metal layer (1), a semiconductor layer (2) and a dielectric layer (3), the metal layers (1), the semiconductor layers (2) and the dielectric layers (3) are sequentially arranged from top to bottom, the metal layers (1) are periodic metal nanoparticle arrays, the semiconductor layers (2) are periodic semiconductor nano-pillar arrays, and the dielectric layers (3) are periodic dielectric nano-pillar arrays.

2. The structure for improving the quality factor of a refractive index sensing device as claimed in claim 1, wherein the metal nanoparticle array of the metal layer (1), the semiconductor nanorod array of the semiconductor layer (2) and the dielectric nanorod array of the dielectric layer (3) have the same period and symmetry, and the period is 300-2000 nm.

3. The refractive index sensing device quality factor improving structure according to claim 1 or 2, wherein the material of the metal nanoparticle array of the metal layer (1) is any one of gold, silver, copper and aluminum, the shape of the metal nanoparticles is spherical, hemispherical or cylindrical, and the diameter of the metal nanoparticles is less than 300 nm.

4. The structure for improving the quality factor of the refractive index sensing device according to claim 1 or 2, wherein the material of the semiconductor nano-pillar array of the semiconductor layer (2) is any one of silicon and germanium, and the shape of the semiconductor nano-pillar is cylindrical or trapezoidal pillar.

5. The structure for improving the quality factor of the refractive index sensing device according to claim 1 or 2, wherein the material of the dielectric nano-pillar array of the dielectric layer (3) is any one of silicon dioxide, titanium dioxide, silicon nitride and magnesium fluoride, and the shape of the dielectric nano-pillar is cylindrical or trapezoidal pillar.

6. The refractive index sensing device quality factor improving structure according to claim 1 or 2, wherein the material of the substrate (4) is any one of quartz, glass, and silicon.

7. A method for testing a structure for improving the quality factor of a refractive index sensing device by using the structure as claimed in any one of claims 1 to 6, comprising the following steps:

(1) utilizing FDTD Solutions micro-nano optical simulation software to construct a physical model of a periodic unit in the structure for improving the quality factor of the refractive index sensing device, then setting periodic boundary conditions on the peripheral boundary of the unit structure, setting completely absorbing boundary conditions on the upper boundary and the lower boundary of the unit structure, setting a beam of vertical incidence light source on the upper surface of the physical model, and calculating the transmission spectrum curve and the reflection spectrum curve of the corresponding physical model in a visible light-near infrared band;

(2) according to the transmission spectrum in the step (1), sequentially setting different background refractive indexes from small to large, and calculating different transmission spectrum curves corresponding to the different background refractive indexes;

(3) obtaining corresponding wavelengths according to the minimum values of different transmission spectrum curves, drawing the wavelengths corresponding to the minimum values of the different transmission spectrum curves and different refractive indexes into a corresponding relation point diagram, fitting the corresponding relation point diagram into a straight line diagram in a linear fitting mode, and then dividing the refractive index change value by the wavelength change value to obtain sensitivity;

(4) and (4) obtaining a transmission spectrum bandwidth according to the transmission spectrum curve, and then dividing the sensitivity obtained in the step (3) by the transmission spectrum bandwidth to obtain the quality factor.

8. The method for testing using a structure for improving the quality factor of a refractive index sensing device according to claim 7, wherein the different background refractive index in the step (2) is a gas refractive index or a liquid refractive index.

Technical Field

The invention relates to a structure for improving the quality factor of a refractive index sensing device and a testing method, belonging to the technical field of devices for improving the quality factor of the refractive index of a sensor.

Background

The periodic metal nanoparticle array can generate a highly enhanced local electromagnetic field due to support of plasmon lattice resonance, and has a wide application prospect in the field of high-performance sensing. The sensing performance of a plasmon-based lattice resonance sensor is mainly determined by a quality factor, which is defined as the sensitivity of plasmon lattice resonance to the surrounding medium environment divided by the plasmon lattice resonance bandwidth (full width at half maximum), and it is obvious that the quality factor can be improved by increasing the sensitivity and/or decreasing the plasmon lattice resonance bandwidth.

However, the plasmon lattice resonance characteristics are very sensitive to changes in the structural parameters of the array and the medium environment, so that in practical applications, since the substrate material supporting the metal nanoparticle array has a higher refractive index than air, the metal surface electromagnetic field in contact with the substrate can be coupled into the medium substrate. This weakens the corresponding electromagnetic field strength and increases the bandwidth of resonance, so that plasmon lattice resonance is suppressed, and it is difficult to distinguish the peak position shift of several nanometers or even several tens of nanometers in actual detection, thereby failing to be effectively and accurately used for sensing analysis. Therefore, the substrate effect is one of the key technical problems restricting the development of the metal plasmon lattice resonant structure sensor.

In order to overcome the technical problems, typically, "Enhanced nanoplasmonic optical sensors with reduced substrates" published in Nano Letters "on page 3893-3898 of 11 th and 3898 of volume 8 of 2008, alexandredmiteriev et al have designed a gold nanoplate array structure supported on a silica nanoplate, and found that the electromagnetic field on the surface of the gold nanoplate is significantly Enhanced, and the sensing sensitivity of the gold nanoplate array is improved to a certain extent. In a recent work (3 months 2020) (x.huang, c.lou, H.Zhang,H.Yang,“Effects ofdifferentstructural parameters and the medium environment on plasmoniclattice resonance formed by Agnanospheres on SiO₂nanopillar arrays, "chinese optics Letters (2020)18(3),33601), yellow minipellets et al demonstrate that silver nanosphere arrays supported on silica nanopillars can form plasmon lattice resonances and produce highly enhanced localized electromagnetic fields. However, when the structure is used for sensing detection, the problem of wide bandwidth (15nm) still exists, so that the quality factor is small. Therefore, the bandwidth of plasmon lattice resonance needs to be further reduced, and the quality factor needs to be further improved.

Disclosure of Invention

In order to solve the problems of wide bandwidth and small quality factor of the metal plasmon lattice resonance structure sensor in the background technology, the invention provides a structure for improving the quality factor of a refractive index sensing device and a test method.

The invention provides a structure for improving the quality factor of a refractive index sensing device, which comprises a substrate and a plurality of composite layers arranged in an array manner and positioned on the surface of the substrate, wherein each composite layer comprises a metal layer, a semiconductor layer and a dielectric layer, the metal layers, the semiconductor layers and the dielectric layers are sequentially arranged from top to bottom, the metal layers are periodic metal nanoparticle arrays, the semiconductor layers are periodic semiconductor nano-column arrays, and the dielectric layers are periodic dielectric nano-column arrays.

Preferably, the metal nanoparticle array of the metal layer, the semiconductor nanorod array of the semiconductor layer and the dielectric nanorod array of the dielectric layer have the same period and symmetry, and the period is 300-2000 nm.

Preferably, the material of the metal nanoparticle array of the metal layer is any one of gold, silver, copper and aluminum, the shape of the metal nanoparticles is spherical, hemispherical or cylindrical, and the diameter of the metal nanoparticles is less than 300 nm.

Preferably, the material of the semiconductor nano-pillar array of the semiconductor layer is any one of silicon and germanium, and the semiconductor nano-pillar is cylindrical or trapezoidal pillar in shape.

Preferably, the dielectric nano-pillar array of the dielectric layer is made of any one of silicon dioxide, titanium dioxide, silicon nitride and magnesium fluoride, and the shape of the dielectric nano-pillar is cylindrical or trapezoidal columnar.

Preferably, the material of the substrate is any one of quartz, glass and silicon.

A test method for utilizing the structure for improving the quality factor of the refractive index sensing device specifically comprises the following steps:

(1) utilizing FDTD Solutions micro-nano optical simulation software to construct a physical model of a periodic unit in the structure for improving the quality factor of the refractive index sensing device, then setting periodic boundary conditions on the peripheral boundary of the unit structure, setting completely absorbing boundary conditions on the upper boundary and the lower boundary of the unit structure, setting a beam of vertical incidence light source on the upper surface of the physical model, and calculating the transmission spectrum curve and the reflection spectrum curve of the corresponding physical model in a visible light-near infrared band;

(2) according to the transmission spectrum in the step (1), sequentially setting different background refractive indexes from small to large, and calculating different transmission spectrum curves corresponding to the different background refractive indexes;

(3) obtaining corresponding wavelengths according to the minimum values of different transmission spectrum curves, drawing the wavelengths corresponding to the minimum values of the different transmission spectrum curves and different refractive indexes into a corresponding relation point diagram, fitting the corresponding relation point diagram into a straight line diagram in a linear fitting mode, and then dividing the refractive index change value by the wavelength change value to obtain sensitivity;

(4) and (4) obtaining a transmission spectrum bandwidth according to the transmission spectrum curve, and then dividing the sensitivity obtained in the step (3) by the transmission spectrum bandwidth to obtain the quality factor.

Preferably, the different background refractive index in step (2) is a gas refractive index or a liquid refractive index.

The structure for improving the quality factor of the refractive index sensing device has the beneficial effects that:

1. the structure for improving the quality factor of the refractive index sensing device supports adjustable plasmon lattice resonance, the plasmon lattice resonance has narrower bandwidth, can effectively realize a high-enhanced local electromagnetic field, is very sensitive to the surrounding medium environment, and has wide application prospect in the field of high-performance sensing.

2. Compared with other existing plasmon lattice resonance structure sensors, the structure provided by the invention provides more regulation and control degrees of freedom. By utilizing the multi-coupling effect between the localized surface plasmon resonance of the metal nanoparticles, the Mie resonance of the semiconductor nano-columns and the diffraction waves of the periodic array and the substrate effect weakened by the dielectric nano-columns, the plasmon lattice resonance with higher sensitivity and extremely narrow bandwidth can be obtained, so that the problem of wider bandwidth of the traditional metal plasmon lattice resonance structure sensor is solved, the effect on improving the quality factor of a refraction rate sensing device is obvious, and the metal plasmon lattice resonance structure sensor has wide application in the fields of biology, medicine, food and the like.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.

In the drawings:

FIG. 1 is a schematic diagram of a structure for improving the quality factor of a refractive index sensing device according to the present invention;

in the figure: 1-a metal layer; 2-a semiconductor layer; 3-a dielectric layer; 4-a substrate; 5-vertical direction incident light.

FIG. 2 is a schematic diagram of a transmission spectrum curve for calculating the background refractive index of the liquid detected by the refractive index sensing device in example 1 by using FDTD Solutions software.

Fig. 3 is a line graph obtained by plotting a correspondence point diagram obtained by detecting wavelengths corresponding to minimum values of different transmission spectrum curves and different liquid background refractive indexes by the refractive index sensing device in example 1 and fitting the correspondence point diagram in a linear fitting manner.

FIG. 4 is a graph showing a transmission spectrum curve for detecting the background refractive index of a liquid by using FDTD Solutions software in the refractive index sensor device of comparative example 1.

Fig. 5 is a line graph obtained by plotting a correspondence point diagram obtained by detecting the wavelengths corresponding to the minimum values of different transmission spectrum curves and different liquid background refractive indexes by the refractive index sensor device of comparative example 1 and fitting the correspondence point diagram in a linear fitting manner.

Detailed Description

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings: