CN104950545A - Method for motivating surface plasma waves and excimers on non-metallic material and medium interfaces - Google Patents

Abstract

The invention provides a method for exciting surface plasmon waves at the interface between a non-metal material and a medium, comprising the following steps: using a predetermined non-metal material such as gallium arsenide to select the medium and the incident electromagnetic wave as an electromagnetic excitation source, the non-metal material, The medium and the wavelength of the incident electromagnetic wave meet the following conditions: Re(ε _m )<0 and |ε _m |>ε _d , ε _m represents the relative permittivity of non-metallic materials, and Re(ε _m ) represents the relative permittivity of non-metallic materials The real part of the dielectric constant, ε _d represents the relative permittivity of the medium, |ε _m | represents the absolute value of ε _m ; and the predetermined non-metallic material is excited with the selected incident electromagnetic wave, in the non-metallic Surface plasmon waves are excited at the interface between the material and the medium. The invention also relates to a method for exciting surface plasmon on the interface between non-metallic material and medium. The surface plasmon is generated by forming a periodic structure on the surface of the non-metallic material and then exciting it with electromagnetic waves.

Description

A method for exciting surface plasmon waves and excitons at the interface between non-metallic materials and medium

technical field

The invention relates to the field of interaction between electromagnetic fields and matter, in particular to a method for exciting surface plasmon waves and exciting plasmons on the interface between non-metallic materials and media.

Background technique

The surface plasmon polariton (SPP) effect is a collective of plasmonic waves formed by a special photon and free electrons generated on the surface of a conductive material that meets specific requirements after it is excited by an electromagnetic field in air or other media. Resonance, its principle is shown in Figure 1. In the prior art, the SPP effect is usually an electromagnetic wave mode formed by the interaction between light and free electrons on the metal surface, as shown in Figure 1, where material 1 contains free electrons on the surface and can be excited to generate surface plasmon waves The conductive material can be called SPP material (that is, SPP material in the figure); material 2 is a dielectric material (that is, dieletric in the figure), usually air.

At present, surface plasmons have been widely used in beam formation, subwavelength structure and plasmonic device preparation, biochemical sensing, etc. However, the excitation of surface plasmons is limited to metal materials, and most metals can only produce strong SPP effects in a certain wavelength range (usually the visible light band).

In semiconductor technology, in order to use the SPP effect, especially its local electric field enhancement function, some existing methods are to coat a layer of metal film on the surface of non-metallic semiconductor materials, such as silver film, and then coat the silver film on this layer A periodic structure that can stimulate the SPP effect is etched out. The disadvantages of this method are: (1) the process is complicated, the repeatability is poor, and the process and cost are increased; (2) the electromagnetic field enhancement effect itself still occurs on the surface of the metal film, and then conducts to the semiconductor material such as gallium arsenide layer , its effect is weakened; (3) the existence of the metal film limits the performance of the GaAs device itself.

Contents of the invention

In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a method for exciting surface plasmon waves at the interface between a non-metallic material and a medium.

Another object of the present invention is to provide a method for exciting surface plasmons at the interface between a non-metallic material and a medium.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A method for exciting surface plasmon waves at an interface between a non-metallic material and a medium, comprising the following steps:

Using a predetermined non-metallic material to select the medium and the incident electromagnetic wave as the electromagnetic excitation source, the non-metallic material, the medium and the wavelength of the incident electromagnetic wave meet the following conditions:

Re(ε _m )<0 and |ε _m |>ε _d ,

In the formula, ε _m represents the relative permittivity of non-metallic materials, Re(ε _m ) represents the real part of the relative permittivity of non-metallic materials, ε _d represents the relative permittivity of the medium, |ε _m | represents ε _m the absolute value of ; and

The predetermined non-metallic material is excited by the selected incident electromagnetic wave, and a surface plasmon wave is excited on the interface between the non-metallic material and the medium.

In a further embodiment, the predetermined non-metallic material is a semiconductor material.

In a further embodiment, the predetermined non-metal material is gallium arsenide.

In a further embodiment, the medium is air, and the incident electromagnetic wave adopts ultraviolet rays within a wavelength range of 124.6nm-262.1nm.

According to the improvement of the present invention, another aspect of the present invention is to propose a method for exciting surface plasmons on the interface between a non-metallic material and a medium, comprising the following steps:

Using a predetermined non-metallic material to select the medium and the incident electromagnetic wave as the electromagnetic excitation source, the non-metallic material, the medium and the wavelength of the incident electromagnetic wave meet the following conditions:

Re(ε _m )<0 and |ε _m |>ε _d ,

In the formula, ε _m represents the relative permittivity of non-metallic materials, Re(ε _m ) represents the real part of the relative permittivity of non-metallic materials, ε _d represents the relative permittivity of the medium, |ε _m | represents ε _m the absolute value of

forming a periodic structure on the surface of the predetermined non-metallic material;

The periodic structure on the non-metallic material is excited by the selected incident electromagnetic wave, and surface plasmons are excited on the interface between the non-metallic material and the medium.

In a further embodiment, the period length of the periodic structure is calculated according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; SP</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}}<span\; class="notranslate">\; ,</span>$

In the formula, λ _SP represents the period length of the periodic structure, and λ ₀ represents the wavelength of the incident electromagnetic wave in vacuum.

In a further embodiment, a periodic structure is formed on one or both surfaces of the predetermined non-metallic material.

In a further embodiment, the predetermined non-metallic material is a semiconductor material.

In a further embodiment, the predetermined non-metal material is gallium arsenide.

In a further embodiment, the medium is air, and the incident electromagnetic wave adopts ultraviolet rays within a wavelength range of 124.6nm-262.1nm.

In a further embodiment, the periodic structure is one of a concentric ring periodic structure and a striped periodic structure.

From the above technical solutions of the present invention, it can be seen that the method for exciting surface plasmon waves and plasmons on the interface between non-metallic materials and media proposed by the present invention, compared with the prior art, has significant effects in that:

1) Non-metallic materials are used to excite surface plasmon waves and surface plasmon polaritons, which breaks through the limitations of using metals to excite surface plasmon waves and surface plasmon polaritons, and expands the application of surface plasmon waves to almost all materials;

2) The use of non-metallic materials can excite the surface plasmon phenomenon, which greatly simplifies the previous process of etching metal films on the surface of non-metallic materials, and realizes that only non-metallic materials need to be directly realized without metal films. Plasmon effect;

3) The use of non-metallic materials to realize surface plasmons can use the mature semiconductor process technology at this stage to process non-metallic materials, significantly improving product processing accuracy and processing quality rate;

4) By using the method of the present invention, combined with the negative refractive index materials at the present stage, the surface plasmon phenomenon can be excited in a wide range of wavelengths, so that this technology can be put into most product processes, greatly expanding the surface plasmon scope of application;

5) The use of non-metallic materials to realize the surface plasmon phenomenon greatly compensates for the limitation of the wavelength range of the surface plasmon excited by the metal material (the surface plasmon waves excited by the commonly used metal materials are generally limited to the visible light band), The wavelength range of the surface plasmon polariton application is expanded, thus making a good supplement for the application of the deep ultraviolet band and other wavelength ranges.

Description of drawings

Fig. 1 is a schematic diagram of the principle of surface plasmon wave generation in the present invention.

FIG. 2 is a schematic diagram of the absolute value of the dielectric constant and the real part of the dielectric constant of a semiconductor material gallium arsenide.

Fig. 3 is an example diagram of a periodic structure used in an embodiment of the present invention, wherein diagram (a) is a top view, and diagram (b) is a side view.

Fig. 4 is a schematic diagram of a reference structure for comparison with the periodic structure shown in Fig. 3, in which (a) is a top view and (b) is a side view.

Fig. 5 is an angle distribution diagram of the electric field at the far field obtained by using the periodic structure in Fig. 3 under 248nm excitation.

Fig. 6 is a diagram of the angular distribution of the electric field at the far field obtained by using the reference structure of Fig. 4 under the excitation of 248nm.

Fig. 7 is another example diagram of the periodic structure used in an embodiment of the present invention, wherein (a) is a top view, and (b) is a side view.

Detailed ways

In order to better understand the technical content of the present invention, specific embodiments are given together with the attached drawings for description as follows.

As shown in Figure 1, according to a preferred embodiment of the present invention, a method for exciting surface plasmon waves at the interface between a non-metallic material and a medium comprises the following steps:

Using a predetermined non-metallic material to select the medium and the incident electromagnetic wave as the electromagnetic excitation source, the non-metallic material, the medium and the wavelength of the incident electromagnetic wave meet the following conditions:

Re(ε _m )<0 (Formula 1)

And |ε _m |>ε _d (Equation 2),

In the formula, ε _m represents the relative permittivity of non-metallic materials, Re(ε _m ) represents the real part of the relative permittivity of non-metallic materials, ε _d represents the relative permittivity of the medium, |ε _m | represents ε _m the absolute value of ; and

The predetermined non-metallic material is excited by the selected incident electromagnetic wave, and a surface plasmon wave is excited on the interface between the non-metallic material and the medium.

As an optional implementation manner, the medium may be selected from one of materials with a negative dielectric constant or a material with a positive dielectric constant, such as air, water, and the like.

More preferably, the predetermined non-metallic material is a semiconductor material. In this embodiment, gallium arsenide (GaAs) is taken as an example to describe the implementation of the method in the foregoing embodiments in detail.

As shown in Figure 2, it is a schematic diagram of the real part of the dielectric constant and the absolute value of the dielectric constant of a semiconductor material gallium arsenide, wherein the solid line represents the real part curve of the dielectric constant of gallium arsenide, according to the aforementioned formula (1), The two points A and B are two points where the real part of the dielectric constant of gallium arsenide is equal to 0, where the coordinates of point A are (111.7, 0), and the coordinates of point B are (262.1, 0), it can be clearly seen from the above figure It is shown that when the wavelength is between 111.7nm and 262.1nm, the real part of the dielectric constant of gallium arsenide is less than 0, and the dielectric constant of gallium arsenide at this time satisfies the formula (1).

In Figure 2, the dotted line represents the absolute value curve of the dielectric constant of gallium arsenide. According to formula (2), here, air is selected as the medium in contact with gallium arsenide, and the dielectric constant of air is 1. Point C It is the point where the absolute value of the dielectric constant of gallium arsenide is equal to 1, where the coordinate of point C is (124.6, 1), then according to the above figure, when the wavelength is greater than 124.6nm, the absolute value of the dielectric constant of gallium arsenide is greater than 1, at this time, the dielectric constant of gallium arsenide satisfies the formula (2).

Therefore, when the wavelength satisfies the above two ranges at the same time, the dielectric constant of gallium arsenide meets the conditions for generating surface plasmon waves, that is, the wavelength range of the incident electromagnetic wave as the electromagnetic excitation source is [124.6, 262.1], that is, 124.6～ 262.1nm.

In an alternative embodiment, for the convenience of computer simulation verification, the wavelength range can be selected as [125, 260], that is, 125-260nm for subsequent computer simulation, and this waveband is electromagnetic waves in the ultraviolet waveband.

As another aspect of the present invention, it also relates to a method for exciting surface plasmons at the interface between a non-metallic material and a medium. The element needs to form a periodic structure on the surface of the non-metallic material, and then use the aforementioned selected electromagnetic wave to excite the periodic structure on the non-metallic material, and excite surface plasmons on the interface between the non-metallic material and the medium.

A periodic structure refers to a periodic multiple structure formed around the center of the structure and at the periphery, such as concentric rings, stripes, shape, U shape, status etc.

As an optional implementation manner, a via hole, such as a circular via hole, may be designed at the center of the periodic structure.

As an optional embodiment, the aforementioned periodic structure may be formed on one surface of the non-metallic material, or the periodic structure may be formed on both surfaces.

In some embodiments, in order to enhance the generation of surface plasmons, the period length of the aforementioned periodic structure is calculated and defined according to the following formula:

${\mathrm{\&lambda;}}_{\mathrm{SP}}={\mathrm{\&lambda;}}_0\sqrt{\frac{{\mathrm{\&epsiv;}}_d+{\mathrm{\&epsiv;}}_m}{{\mathrm{\&epsiv;}}_d{\mathrm{\&epsiv;}}_m}}$ (Formula 3),

In the formula, λ _SP represents the period length of the periodic structure, and λ ₀ represents the wavelength of the incident electromagnetic wave in vacuum.

Figure 3 shows an example of forming a periodic structure on the surface of GaAs, in which GaAs is in the form of a thin film, a central circular via is formed on the surface, and periodic multiple layers are formed on the periphery of the circular via. concentric rings.

As an embodiment, in Fig. 3, the gallium arsenide film thickness is 120nm, the radius of the circular via hole in the center is 60nm, the radius of the outer circle of the first concentric ring away from the central circular via hole is 300nm, and the radius of the inner circle is 300nm. is 180nm, the etching depth on the film is 24nm, the distance between the second ring and the first ring is 240nm, and then the outer circle radius and inner circle radius of the outer circle are calculated according to the above formula 3, thus forming a periodic structure. In this manner, a periodic structure can be formed on one surface of the gallium arsenide thin film.

The etched periodic structure of the lower layer of the gallium arsenide thin film is completely symmetrical to the upper layer structure. As shown in FIG. 3 , the concentric ring periodic structure is a similar bull's-eye structure.

FIG. 4 is a schematic diagram of a reference structure for comparison with the periodic structure shown in FIG. 3 . In this reference structure, there is only one central circular via hole on the surface of the gallium arsenide film.

In Fig. 3 and Fig. 4, the arrow line below indicates the direction of the incident electromagnetic wave, and the arrow line above indicates the direction of the outgoing electromagnetic wave after passing through the film.

Figure 5 shows the angle distribution diagram (simulation effect diagram) of the electric field in the far field obtained by using the periodic bull's-eye structure in Figure 3 under the excitation of 248nm ultraviolet electromagnetic waves, which shows that the periodic structure passes through the surface of gallium arsenide ( The SPP effect generated by the bull's-eye structure) directly excites surface plasmons on the surface of GaAs, and the electric field intensity is greatly enhanced in the center of the film.

Figure 6 shows the angle distribution diagram (simulation effect diagram) of the electric field at the far field obtained by using the reference structure in Figure 4 under the excitation of 248nm ultraviolet electromagnetic waves. It shows that without a periodic structure, the SPP effect is not excited, and the electric field distribution is obviously dispersed.

FIG. 7 is a schematic diagram of another embodiment of a periodic structure, the periodic structure is a striped periodic structure, and the period length of the periodic structure is preferably calculated according to the above formula 3.

Similarly, in the figure, the arrow line below indicates the direction of the incident electromagnetic wave, and the arrow line above indicates the direction of the outgoing electromagnetic wave after passing through the film.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims.

Claims (10)

1. A method for exciting surface plasmon waves at a non-metallic material and a medium interface, characterized in that it may further comprise the steps: Using a predetermined non-metallic material to select the medium and the incident electromagnetic wave as the electromagnetic excitation source, the non-metallic material, the medium and the wavelength of the incident electromagnetic wave meet the following conditions: Re(ε _m )<0 and |ε _m |>ε _d , In the formula, ε _m represents the relative permittivity of non-metallic materials, Re(ε _m ) represents the real part of the relative permittivity of non-metallic materials, ε _d represents the relative permittivity of the medium, |ε _m | represents ε _m the absolute value of ; and The predetermined non-metallic material is excited by the selected incident electromagnetic wave, and a surface plasmon wave is excited on the interface between the non-metallic material and the medium. 2. The method for exciting surface plasmon waves at the interface between a non-metallic material and a medium according to claim 1, wherein the predetermined non-metallic material is a semiconductor material. 3. A method for exciting surface plasmon waves at the interface between a non-metallic material and a medium, characterized in that the predetermined non-metallic material is gallium arsenide. 4. A method for exciting a surface plasmon wave at the interface between a non-metallic material and a medium, characterized in that the medium is air, and the incident electromagnetic wave adopts ultraviolet light within a wavelength range of 124.6nm to 262.1nm. 5. A method for exciting surface plasmons on the interface between a non-metallic material and a medium, comprising the following steps: Using a predetermined non-metallic material to select the medium and the incident electromagnetic wave as the electromagnetic excitation source, the non-metallic material, the medium and the wavelength of the incident electromagnetic wave meet the following conditions: Re(ε _m )<0 and |ε _m |>ε _d , In the formula, ε _m represents the relative permittivity of non-metallic materials, Re(ε _m ) represents the real part of the relative permittivity of non-metallic materials, ε _d represents the relative permittivity of the medium, |ε _m | represents ε _m the absolute value of forming a periodic structure on the surface of the predetermined non-metallic material; The periodic structure on the non-metallic material is excited by the selected incident electromagnetic wave, and surface plasmons are excited on the interface between the non-metallic material and the medium. 6. The method for exciting surface plasmons at the interface between a non-metallic material and a medium according to claim 5, wherein the period length of the periodic structure is calculated according to the following formula: ${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; SP</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}}<span\; class="notranslate">\; ,</span>$ In the formula, λ _SP represents the period length of the periodic structure, and λ ₀ represents the wavelength of the incident electromagnetic wave in vacuum. 7. The method for exciting surface plasmons at the interface between a non-metallic material and a medium according to claim 5, wherein a periodic structure is formed on one or both surfaces of the predetermined non-metallic material. 8 . The method for exciting surface plasmons at the interface between a non-metallic material and a medium according to claim 5 , wherein the predetermined non-metallic material is gallium arsenide. 9. The method for exciting surface plasmons at the interface between a non-metallic material and a medium according to claim 8, wherein the medium is air, and the incident electromagnetic wave adopts ultraviolet rays within the wavelength range of 124.6nm to 262.1nm . 10 . The method for exciting surface plasmons at the interface between non-metallic materials and media according to claim 5 , wherein the periodic structure is one of a concentric ring periodic structure and a striped periodic structure. 11 .