CN118759618A - Broadband absorption devices based on phase change materials - Google Patents

Abstract

The invention provides a broadband absorption device based on a phase change material, which comprises a broadband absorption cavity structure, a broadband absorption cavity structure and a broadband absorption structure, wherein the broadband absorption cavity structure comprises an anti-reflection layer, a phase change layer and a metal layer; the lithium tantalate single-chip structure is positioned below the broadband absorption cavity structure; when light rays are emitted to the broadband absorption cavity structure, the broadband absorption cavity structure is used for converting absorbed light energy into heat energy, the lithium tantalate single-chip structure is used for converting the heat energy into electric energy through a pyroelectric effect and outputting current, so that the state of the phase change layer is changed according to the current, and the absorbed light rays are regulated. The invention provides a dynamically adjustable broadband absorption structure which is insensitive to angles, simple in structure and easy to integrate.

Description

Broadband absorption devices based on phase change materials

Technical Field

The present invention relates to the technical field of phase change materials, and in particular to a broadband absorption device based on phase change materials.

Background Art

Broadband absorbers have attracted a lot of attention due to their wide applications in infrared stealth, optical or thermal detection, solar cells, broadband thermal radiators, etc., and can also be used to recover waste heat for energy applications. Some of these approaches use materials such as carbon nanotubes to absorb light over a very wide frequency range, but this involves micron-thick structures and there is little control over the spectral range. To achieve controllable absorption over a broadband range, most of them focus on confining multiple plasmonic nanostructures with overlapping resonances into subwavelength pixels. However, although these structures can achieve very high absorption through field confinement and tolerance to angles, only a limited number of absorbing structures can be put into one area, which limits the bandwidth, complicates the manufacturing process, and has narrow absorption.

In the existing broadband absorber structure, the broadband absorber structure mainly adopts the structure of metasurface or carbon nanotube, which is complex and sensitive to angle changes. Or the broadband absorber structure is composed of dielectric and metal, but the device cannot be adjusted once it is made. Therefore, it is of great practical significance to design a broadband absorber technology that is both dynamically adjustable.

Summary of the invention

The present invention provides a broadband absorption device based on phase change material, which is used to solve the defects of the broadband absorber in the prior art, such as complex structure, sensitivity to angle change, and unadjustable absorption range, and realizes a dynamically adjustable broadband absorption structure based on phase change material, which is insensitive to angle, simple in structure, and easy to integrate.

The present invention provides a broadband absorption device based on phase change material, comprising:

A broadband absorption cavity structure, comprising an anti-reflection layer, a phase change layer and a metal layer, wherein the broadband absorption cavity structure utilizes the absorption characteristics and dynamic adjustable characteristics of the phase change material and a semiconductor material having a K value greater than a first preset threshold value to jointly form a broadband absorber to absorb and adjust light;

The anti-reflection layer includes a plurality of dielectric materials with a refractive index gradient, wherein the K value of the dielectric material is less than 1, and the refractive index of the plurality of dielectric materials presents a gradient distribution, from top to bottom, from large to small;

A lithium tantalate single crystal structure, located below the broadband absorption cavity structure;

When light hits the broadband absorption cavity structure, the broadband absorption cavity structure is used to convert the absorbed light energy into thermal energy, and the lithium tantalate single crystal structure is used to convert the thermal energy into electrical energy through the pyroelectric effect and output current to change the state of the phase change layer according to the size of the current to adjust the absorbed light.

According to a broadband absorption device based on phase change material provided by the present invention, the broadband absorption cavity structure comprises multiple metal layers, and the effective N and K of the multiple metal layers are both greater than 1, and the larger the better;

The medium in the anti-reflection layer has a refractive index gradient, and the refractive index n value has a gradient distribution from top to bottom, from large to small, and the K value tends to 0. A plurality of dielectric materials with K values tending to 0 constitute the anti-reflection layer structure.

According to a broadband absorption device based on phase change material provided by the present invention, the broadband absorption cavity structure includes an FP cavity formed by the metal layer and the dielectric layer sandwiching the phase change layer, or an FP cavity formed by the phase change layer and the metal layer.

According to a broadband absorption device based on phase change material provided by the present invention, the broadband absorption cavity structure includes a reflection layer, a phase change layer, a dielectric layer, a first semiconductor material layer, a second semiconductor material layer and a metal layer arranged in sequence from top to bottom.

According to a broadband absorption device based on phase change material provided by the present invention, the first semiconductor layer is a material such as Ge, Si, etc., whose N and K values are both greater than 1, and whose main function is to absorb light; the second semiconductor layer is a material such as Cr, W, etc., whose N value is greater than 1 and whose K value is smaller; the metal layer is a conductive material such as W and Ag, etc., and has stable performance, and this layer mainly provides electrode drive and generates heat to drive the state change of the phase change material.

According to a broadband absorption device based on phase change material provided by the present invention, the voltage applied to the metal layer is regulated according to the magnitude of the current, and the crystallization and amorphization ratio of the phase change material in the phase change layer is controlled to regulate the absorption of the light.

According to a broadband absorption device based on phase change material provided by the present invention, the thickness of the phase change material used in the phase change layer is less than 1 micron.

According to a broadband absorption device based on phase change material provided by the present invention, there are multiple phase change layers, each phase change layer includes a phase change material layer and electrode layers located on both sides of the phase change material layer, and the electrode layers between two adjacent phase change material layers are shared.

According to a broadband absorption device based on phase change material provided by the present invention, the phase change material used in the phase change layer is one or more of alloys such as GeTe, SbTe, SnSb, AgSbTe, InSbTe, GeSb and GST, wherein the percentage of each atom is adjustable, and the K value of the phase change material is greater than 0.5;

The material used for the anti-reflection layer is a medium with a lower K value, such as TIO2, Ta2O5, MgF2, and ZnS.

According to a broadband absorption device based on phase change material provided by the present invention, the thickness of the reflective layer is less than 1 micron, the thickness of the phase change layer is less than 500nm, the thickness of the first semiconductor material layer is less than 200nm and greater than 10nm, the thickness of the second semiconductor material layer is less than 500nm and greater than 50nm, the thickness of the metal layer is less than 1 micron, and the thickness of the lithium tantalate single crystal structure is not limited to 75 microns.

The broadband absorption device based on phase change material provided by the present invention converts the absorbed light energy into heat energy through a broadband absorption cavity structure, and the lithium tantalate single crystal structure converts the heat energy into electrical energy through the pyroelectric effect, outputs current and changes the state of the phase change layer according to the magnitude of the current, thereby realizing wide-band absorption adjustment, and can adjust the size of the absorption range as needed, with a wide adjustment direction, insensitive to angles, simple structure, and easy integration, thus overcoming the inherent limitations of existing structures, having great technological advancement significance, and providing new possibilities for the further development of broadband absorption technology.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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.

FIG1 is a schematic structural diagram of a broadband absorption device based on phase change material provided by the present invention;

FIG2 is a schematic diagram of the structure of a broadband absorption cavity in a broadband absorption device based on phase change material provided by the present invention;

3 is a schematic diagram of the absorption spectrum of GSST in a broadband absorption device based on phase change materials provided by the present invention when it is in an amorphous state;

4 is a schematic diagram of the absorption spectrum of GSST in a broadband absorption device based on phase change materials provided by the present invention when it is in a crystalline state;

FIG5 is an absorption angle insensitivity diagram of GSST in an amorphous state in a broadband absorption device based on a phase change material provided by the present invention;

FIG. 6 is a graph showing the absorption angle insensitivity of GSST in a broadband absorption device based on phase change materials provided by the present invention when the GSST is in a crystalline state.

Reference numerals:

101: the first anti-reflection layer in the broadband absorption cavity structure; 102: the second anti-reflection layer in the broadband absorption cavity structure; 103: the phase change layer in the broadband absorption cavity structure; 104: the dielectric layer in the broadband absorption cavity structure; 105: the first semiconductor material layer in the broadband absorption cavity structure; 106: the second semiconductor material layer in the broadband absorption cavity structure; 107: the metal layer in the broadband absorption cavity structure; 201: the first anti-reflection layer in the broadband absorption device based on phase change material; 202: the second anti-reflection layer in the broadband absorption device based on phase change material; 203: the phase change layer in the broadband absorption device based on phase change material; 204: the dielectric layer in the broadband absorption device based on phase change material; 205: the first semiconductor material layer in the broadband absorption device based on phase change material; 206: the second semiconductor material layer in the broadband absorption device based on phase change material; 207: the metal layer in the broadband absorption device based on phase change material; 208: the lithium tantalate single crystal structure in the broadband absorption device based on phase change material.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

The following describes a broadband absorption device based on phase change material of the present invention in conjunction with FIG1, comprising:

A broadband absorption cavity structure, comprising an anti-reflection layer, a phase change layer 203 and a metal layer 207;

A lithium tantalate single crystal structure 208, located below the broadband absorption cavity structure;

When light hits the broadband absorption cavity structure, the broadband absorption cavity structure is used to convert the absorbed light energy into thermal energy, and the lithium tantalate single crystal structure is used to convert the thermal energy into electrical energy through the pyroelectric effect and output current to change the state of the phase change layer according to the size of the current to adjust the absorbed light.

The phase change layer 203 includes a phase change material. The order of combining metal and phase change material is not limited. The metal layer 207 can be arranged on both sides of the phase change material. The metal layer plays the role of forming a FP (Fabry-perot, resonant cavity) cavity with the phase change material and controlling the phase change of the phase change material. By applying voltage to the metal layers on both sides of the phase change material, the crystal structure of the phase change material can be changed, thereby adjusting the proportion of light absorption by the broadband absorber structure.

The broadband absorber cavity structure mainly includes an anti-reflection layer, a phase change layer 203 and a metal layer 207. When the three are combined, the broadband absorber cavity structure can achieve an adjustable absorption effect in the visible and infrared. The metal layer 207 has a high loss characteristic.

Below the broadband absorber cavity structure is a lithium tantalate single crystal structure 208. The absorbed light energy will be converted into heat energy and transmitted to the pyroelectric material. The pyroelectric material converts the heat energy into electrical energy through the pyroelectric effect, so it can output current for use in solar cells and broadband thermal radiators.

Through this design, the broadband absorption structure can be adjusted according to actual needs and the proportion of target light absorption can be adjusted. The maximum absorption can reach more than 90%, and the absorption range can be extended to after 400nm. It can also be made insensitive to angles to meet the needs of broadband absorbers for absorbers in infrared stealth, optical or thermal detection, solar cells, broadband thermal radiators, etc.

This embodiment converts the absorbed light energy into heat energy through a broadband absorption cavity structure, and the lithium tantalate single crystal structure converts heat energy into electrical energy through the pyroelectric effect, outputs current and changes the state of the phase change layer according to the magnitude of the current, thereby realizing wide-band absorption adjustment. The size of the absorption range can be adjusted as needed, the adjustment direction is wide, it is insensitive to angles, the structure is simple, and it is easy to integrate. It overcomes the inherent limitations of the existing structure, has great technological advancement significance, and provides new possibilities for the further development of wide-band absorption technology.

On the basis of the above embodiment, in this embodiment, the extinction coefficient of the metal layer is greater than the first preset threshold, and the refractive index is greater than the second preset threshold;

The medium in the anti-reflection layer has a refractive index gradient, and an absorptivity greater than a third preset threshold.

A dynamically adjustable broadband absorber is composed of an anti-reflection layer, a phase change material and an absorptive metal with a high refractive index and extinction coefficient.

The anti-reflection layer is composed of a medium with a refractive index gradient and high absorptivity, and the regulation is mainly achieved by the phase change material in the phase change layer 203. The metal film with a high refractive index and extinction coefficient and the phase change layer 203 absorb and regulate the light from 400nm to 2500nm.

The phase change material of the phase change layer 203 may include the following chalcogenide compounds and their alloys, including but not limited to GST, GSST, IST, GeSbTe, AgInSbTe, InSbTe, AgSbTe, Ag ₂ In ₄ Sb ₇₆ Te ₁₇ (AIST) and other high-loss and low-refractive-index characteristic phase change materials, which can achieve a wide range of absorption adjustment. In addition, the atomic percentages in the above chemical formulas are variable. The phase change material may further include at least one dopant, such as C and N. Preferably, the phase change material is selected as GSST, which has a large loss in the visible light range, a small refractive index, and good thermal stability.

On the basis of the above embodiments, the broadband absorption cavity structure in this embodiment includes an FP cavity formed by the metal layer 207 and a dielectric layer sandwiching the phase change layer 203 , or an FP cavity formed by the phase change layer 203 and the metal layer 207 .

On the basis of the above embodiment, as shown in FIG2 , the broadband absorption cavity structure in this embodiment includes a first anti-reflection layer 101, a second anti-reflection layer 102, a phase change layer 103, a dielectric layer 104, a first semiconductor material layer 105, a second semiconductor material layer 106 and a metal layer 107 arranged in sequence from top to bottom.

Optionally, the phase change material of the phase change layer 103 is a high-loss, low-refractive-index material, including but not limited to GSST, and the metal layer is Ag, wherein GSST is an ultra-thin phase change material with strong optical loss.

Below the phase change material are the first semiconductor material layer 105 and the second semiconductor material layer 106. The first semiconductor material layer 105 and the second semiconductor material layer 106 may be metals with high extinction coefficients, such as Ge and Cr. The phase change material may be surrounded by dielectric material TiO ₂ above and below.

As shown in FIG. 1 , the broadband absorption device based on phase change material includes a first anti-reflection layer 201, a second anti-reflection layer 202, a phase change layer 203, a dielectric layer 204, a first semiconductor material layer 205, a second semiconductor material layer 206, a metal layer 207 and a lithium tantalate single crystal structure 208 arranged in sequence from top to bottom.

On the basis of the above embodiment, in this embodiment, the optical loss of the first semiconductor material layer 205 is greater than the fourth preset threshold value and the refractive index is greater than the fifth preset threshold value;

The optical loss of the second semiconductor material layer 206 is greater than the fourth preset threshold and the refractive index is greater than the fifth preset threshold.

On the basis of the above embodiment, in this embodiment, the voltage applied to the metal layer 207 is regulated according to the magnitude of the current, and the crystallization and amorphization ratio of the phase change material in the phase change layer 203 is controlled to regulate the absorption of the light.

The phase change material of the phase change layer 203 can be converted between the crystalline state and the amorphous state under electrical stimulation or laser stimulation, so that the transmittance and reflectivity of the phase change layer 203 change. The first anti-reflection layer 201 of the top layer is deposited with transparent lossless material MgF ₂ , and the second anti-reflection layer 202 is deposited with TiO ₂ , and the two together constitute an anti-reflection layer. The phase change layer 203 can control the crystallization state of the phase change material by applying a voltage on the metal layer 207W.

Specifically, when a pulse voltage of medium intensity is applied to W, W will generate heat. Under the action of heat, the temperature of the phase change material rises to a temperature range above the crystallization temperature and below the melting temperature, and is maintained for a certain period of time. At this time, the lattice is orderly arranged to form a crystalline state, realizing the transformation from amorphous to crystalline.

A short and strong voltage is applied to W, which generates high heat in an instant, causing the temperature of the phase change material to rise above the melting temperature, destroying the long-range order of the crystalline state. The pulse falling edge is very short, causing the phase change material to be quickly cooled to below the crystallization temperature, fixing the phase change material in the amorphous state, and realizing the transition from crystalline to amorphous state.

The ratio of light absorption by the narrow-band absorption cavity structure is regulated by the changes in transmittance and reflectivity of the phase change material of the phase change layer 203 when the phase change material transforms between the amorphous state and the crystalline state.

The phase change layer of the phase change broadband absorption cavity structure has very different absorption of light in different states. The phase change material is stable in the crystalline and amorphous states, so the voltage or laser can be removed when the phase change material is in a stable state. Therefore, the power consumption of the entire absorption device during the adjustment process is very low and it is dynamically adjustable.

Based on the above embodiment, the thickness of the phase change material used in the phase change layer 203 in this embodiment is less than 1 micrometer.

The thickness of the phase change material used in the phase change layer 203 is less than 1 micron. Since the increase in the thickness of the phase change material will increase the temperature required for the crystallization of the phase change material, the more suitable thickness is within 1 micron. The phase change material of the phase change layer 203 can be driven by voltage. When driven by voltage, the metal W at the bottom of the narrow-band absorption cavity structure applies voltage to cause the phase change material to undergo phase change.

Based on the above embodiment, in this embodiment, there are multiple phase change layers 203, each phase change layer 203 includes a phase change material layer and electrode layers located on both sides of the phase change material layer, and the electrode layers between two adjacent phase change material layers are shared.

Based on the above embodiment, in this embodiment, the first anti-reflection layer 201 is MgF ₂ , the second anti-reflection layer 202 is TIO ₂ , the phase change layer 203 is GSST, the dielectric layer 204 is TIO ₂ , the first semiconductor material layer 205 is Ge, the second semiconductor material layer 206 is Cr, and the metal layer 207 is W.

On the basis of the above embodiments, in this embodiment, the thickness of the first anti-reflection layer 201 is 90nm, the thickness of the second anti-reflection layer 202 is 50nm, the thickness of the phase change layer 203 is 8nm, the thickness of the dielectric layer 204 is 36nm, the thickness of the first semiconductor material layer 205 is 25nm, the thickness of the second semiconductor material layer 206 is 200nm, the thickness of the metal layer 207 is 200nm, and the thickness of the lithium tantalate single crystal structure 208 is 75 microns.

FIG3 is a schematic diagram of the absorption spectrum of GSST in FIG1 when it is in an amorphous state. FIG4 is a schematic diagram of the absorption spectrum of GSST in FIG1 when it is in a crystalline state. By applying different voltages to the metal layer 207W, the phase change material layer changes from an amorphous state to partial crystallization to complete crystallization. The magnitude of the applied voltage depends on the actual needs, and the absorption ratio of the target light is adjusted according to the actual needs.

As can be seen from FIG. 5 and FIG. 6 , in the broadband absorption device based on phase change material provided by the present invention, the absorption angle insensitivity of GSST in the amorphous state and the amorphous state can reach 70°, and there is no significant difference within the range of 60°.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A broadband absorption device based on phase change material, comprising: A broadband absorption cavity structure, comprising an anti-reflection layer, a phase change layer and a metal layer, wherein the broadband absorption cavity structure utilizes the absorption characteristics and dynamic adjustable characteristics of the phase change material and a semiconductor material having a K value greater than a first preset threshold value to jointly form a broadband absorber to absorb and adjust light; The anti-reflection layer includes a plurality of dielectric materials with a refractive index gradient, wherein the K value of the dielectric material is less than 1, and the refractive index of the plurality of dielectric materials presents a gradient distribution, from top to bottom, from large to small; A lithium tantalate single crystal structure, located below the broadband absorption cavity structure; When light hits the broadband absorption cavity structure, the broadband absorption cavity structure is used to convert the absorbed light energy into thermal energy, and the lithium tantalate single crystal structure is used to convert the thermal energy into electrical energy through the pyroelectric effect and output current to change the state of the phase change layer according to the size of the current to adjust the absorbed light. 2. The broadband absorption device based on phase change material according to claim 1, characterized in that the broadband absorption cavity structure comprises multiple metal layers, and the effective N and K of the multiple metal layers are both greater than 1, and the larger the better; The dielectric absorption rate in the anti-reflection layer is less than 1, the smaller the better, and eventually approaches 0. 3. The broadband absorption device based on phase change material according to claim 1 is characterized in that the broadband absorption cavity structure includes an FP cavity formed by the metal layer and the dielectric layer sandwiching the phase change layer, or an FP cavity formed by the phase change layer and the metal layer. 4. The broadband absorption device based on phase change material according to claim 1 is characterized in that the broadband absorption cavity structure includes a first anti-reflection layer, a second anti-reflection layer, a phase change layer, a dielectric layer, a first semiconductor material layer, a second semiconductor material layer and a metal layer arranged in sequence from top to bottom. 5. The broadband absorption device based on phase change material according to claim 4 is characterized in that the voltage applied to the metal layer is regulated according to the magnitude of the current to control the crystallization and amorphization ratio of the phase change material in the phase change layer to regulate the absorption of the light. 6 . The broadband absorption device based on phase change material according to claim 1 , wherein the thickness of the phase change material used in the phase change layer is less than 1 micron. 7. The broadband absorption device based on phase change material according to claim 1 is characterized in that there are multiple phase change layers, each phase change layer includes a phase change material layer and electrode layers located on both sides of the phase change material layer, and the electrode layer between two adjacent phase change material layers is shared. 8. The broadband absorption device based on phase change material according to claim 4, characterized in that the phase change material used in the phase change layer is one or more of GeTe, SbTe, SnSb, AgSbTe, InSbTe, GeSb and GST alloy, wherein the percentage of each atom is adjustable, and the K value of the phase change material is greater than 0.5; The material used for the anti-reflection layer is a medium having a K value less than a second preset threshold value among TIO2, Ta2O5, MgF2 and ZnS; The first semiconductor material layer is a material of Ge and Si, wherein the N and K values are both greater than 1; The second semiconductor material layer is a material whose N value among Cr and W is greater than 1 and whose K value is less than a third preset threshold value; The metal layer is a conductive material among W and Ag and has stable performance. 9. The broadband absorption device based on phase change material according to claim 8 is characterized in that the thickness of the reflective layer is less than 1 micron, the thickness of the phase change layer is less than 500nm, the thickness of the first semiconductor material layer is less than 200nm and greater than 10nm, the thickness of the second semiconductor material layer is less than 500nm and greater than 50nm, the thickness of the metal layer is less than 1 micron, and the thickness of the lithium tantalate single crystal structure is 75 microns.