Laser-induced phase change radio frequency switch with antireflection layer for enhancing absorption

Abstract

The invention relates to a laser-induced phase change radio frequency switch with an anti-reflection layer for enhancing absorption. The switch comprises a laser light source and a switch structure, the switch structure comprises an anti-reflection passivation layer, a phase change material layer, a metal electrode layer and a dielectric substrate layer. The metal electrode layer and the phase-change material layer are arranged on the dielectric substrate layer, the metal electrode layer is located on the periphery of the phase-change material layer, and the anti-reflection passivation layer is located on the uppermost layer and used for completely covering the phase-change material layer; the anti-reflection passivation layer is a light-transmitting layer, and the anti-reflection passivation layer right above the phase-change material layer is used as a light incident surface of incident laser and an emergent surface of reflected laser; and the laser light source is arranged opposite to the anti-reflection passivation layer so as to induce the phase change material layer to generate phase change based on the anti-reflection passivation layer. The anti-reflection passivation layer is added on the surfaces of the phase change material layer and the metal electrode layer, the material refractive index and thickness of the anti-reflection passivation layer are controlled, laser reflection is reduced, and the problem that the light-operated phase change radio frequency switch is low in laser utilization rate is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of radio frequency switches, and in particular to a laser induced phase change radio frequency switch with an anti-reflection layer for enhanced absorption. Background Art

[0002] Switches are the basic building blocks of many radio frequency (RF) and microwave systems. They are used to control the on and off of RF signals and are an indispensable key part. With the advent of the 5G era, the increase in communication frequency bands has put forward higher requirements for RF switches. The performance of traditional RF switches (PIN diodes and FETs) deteriorates sharply at high frequencies. Therefore, new RF switch technologies are urgently needed to solve this problem. The resistance characteristics of phase change materials are related to their crystalline / amorphous phase states and do not change with frequency. Phase change RF can still maintain good RF performance with low insertion loss and high isolation at high frequencies, providing new technical ideas for millimeter wave and even terahertz RF switches.

[0003] The state switching of the phase change RF switch relies on electric pulses or light pulses as heat sources to control the temperature, thereby controlling the mutual conversion between the amorphous state and the crystalline state of the phase change material to realize the on and off of the switch. In the prior art, compared with the electric excitation method, the light-induced excitation method has a simpler switch structure, avoids the additional capacitance caused by the electric heating path, and has better RF performance; the laser pulse has high energy and can quickly heat the phase change material, so the laser-induced phase change RF switch has a faster switching speed. For example, Aurelian Crunteanu et al. disclosed a GeTe phase change RF switch induced by 248nm wavelength laser, which can achieve high isolation and low insertion loss in the range of 0-67GHz (Aurelian Crunteanu, Laure Huitema, Jean-Chr is tophe Orli ianges, et al. Optimal Switching of GeTe Phase Change Materials for High-Frequency Applications [C]. IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes (IMWS-AMP), 2017). However, the laser of the 248nm wavelength ultraviolet laser source used in this design is bulky, expensive, and has low practicality.

[0004] Char let, I and others have realized a 915nm wavelength laser-induced GeTe phase-change RF switch, providing a new way to realize cheap and high-performance optically excited phase-change RF switches (Char let I, Guerber S, Naoui A, et al. Optical Actuation Performance of Phase-Change RF Switches [J]. IEEE Electron Device Letters, 2024, 45 (3): 500-503.). However, due to the high reflectivity of phase change materials in the infrared band (greater than 60% in the crystalline state and greater than 30% in the amorphous state), the laser energy utilization rate is low, the energy waste is large, and a higher laser energy is required to induce phase change, which is not conducive to the integrated design of small low-power lasers and phase change switches. Summary of the invention

[0005] The object of the present invention is to provide a laser induced phase change radio frequency switch with an anti-reflection layer and enhanced absorption, so as to solve the problem of low laser utilization rate of the optically controlled phase change radio frequency switch.

[0006] To achieve the above-mentioned purpose, the present invention provides a laser-induced phase change radio frequency switch with anti-reflection layer enhanced absorption, comprising: a laser light source and a switch structure;

[0007] The switch structure comprises: an anti-reflection passivation layer, a phase change material layer, a metal electrode layer and a dielectric substrate layer;

[0008] The metal electrode layer and the phase change material layer are arranged on the dielectric base layer, the phase change material layer is located in the middle above the dielectric base layer, the metal electrode layer is located at the periphery of the phase change material layer, and the anti-reflection passivation layer is located at the uppermost layer to completely cover the phase change material layer;

[0009] The anti-reflection passivation layer is a light-transmitting layer, and the anti-reflection passivation layer directly above the phase change material layer serves as a light incident surface for incident laser light and an exit surface for reflected laser light;

[0010] The laser light source is arranged opposite to the anti-reflection passivation layer, so as to induce the phase change of the phase change material layer based on the anti-reflection passivation layer.

[0011] According to one aspect of the present invention, the anti-reflection passivation layer is made of a transparent, insulating material and the melting point of the anti-reflection passivation layer is greater than the phase change temperature of the phase change material layer; wherein the material used to prepare the anti-reflection passivation layer is one or more of aluminum nitride, zinc sulfide, zinc selenide, magnesium fluoride, silicon nitride, silicon dioxide and titanium oxide.

[0012] According to one aspect of the present invention, the anti-reflection passivation layer is a single-layer anti-reflection thin film layer; wherein, the anti-reflection passivation layer uses a material with a refractive index between that of air and the phase change material layer, and by controlling the film thickness of the anti-reflection passivation layer, the reflected light between the air and the anti-reflection passivation layer and the reflected light between the anti-reflection passivation layer and the phase change material layer are canceled out to achieve an anti-reflection effect.

[0013] According to one aspect of the present invention, the anti-reflection passivation layer includes multiple anti-reflection film layers, and the refractive index of each anti-reflection film layer is different, so that the equivalent refractive index of the anti-reflection passivation layer is between air and the phase change material layer.

[0014] According to one aspect of the present invention, the phase change material layer has a resistivity ratio greater than 10 before and after the phase change. 3 Made of phase change material.

[0015] According to one aspect of the present invention, the phase change material layer is made of one or more of germanium telluride, germanium antimony telluride, vanadium dioxide, antimony selenide and antimony telluride.

[0016] According to one aspect of the present invention, the metal electrode layer is an input and output channel for radio frequency signals, and its conductivity is greater than 1×10 7 S / m metal layer.

[0017] According to one aspect of the present invention, the metal electrode layer is made of one or more materials selected from the group consisting of gold, copper and silver;

[0018] The dielectric substrate layer is made of one or more materials selected from the group consisting of glass, silicon carbide, silicon, aluminum nitride and sapphire.

[0019] According to one aspect of the present invention, the thickness of the anti-reflection passivation layer is less than or equal to 1 μm.

[0020] According to one aspect of the present invention, the laser light source is used to generate laser light with a wavelength of 100nm-2000nm;

[0021] The irradiation range of the laser light source covers the phase change material layer.

[0022] According to one solution of the present invention, the present invention adds an anti-reflection passivation layer on the surface of the phase change material layer, which plays a passivation and anti-reflection role at the same time. Passivation refers to protecting the phase change material layer, and anti-reflection refers to reducing the reflection of the phase change material layer to the incident laser through thickness design, thereby improving the utilization rate of laser energy, solving the problem of low laser utilization rate of optically controlled phase change RF switches, and providing the possibility of integrating low-power small lasers with passive phase change RF switches.

[0023] According to one solution of the present invention, the anti-reflection passivation layer of the present invention can not only protect the phase change material layer, but also avoid the loss of laser energy, ensuring that the laser energy passes through the anti-reflection passivation layer as loss-free as possible to irradiate the phase change material layer. In addition, the anti-reflection passivation layer of the present invention also effectively prevents the short circuit of the metal electrode layer through the insulating setting, so as to ensure the stable and reliable operation of the entire switch.

[0024] According to one solution of the present invention, the metal electrode layer is made of a material with an electrical conductivity greater than 1×10 7 The metal of S / m can effectively reduce the resistance loss on the metal electrode layer, so that the present invention has the advantage of low insertion loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of a laser induced phase change radio frequency switch according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram schematically showing the anti-reflection principle of an anti-reflection passivation layer according to an embodiment of the present invention;

[0027] Figure 3 It is a curve schematically showing the change of the surface reflectivity of the phase change material germanium telluride with the laser wavelength;

[0028] Figure 4 Schematically shows the curve of the reflectivity of crystalline germanium telluride after adding the anti-reflection passivation layer in Example 1 as a function of the laser wavelength;

[0029] Figure 5 Schematically shows the curve of the change of the reflectivity of amorphous germanium telluride after adding the anti-reflection passivation layer in Example 1 with the laser wavelength. DETAILED DESCRIPTION

[0030] 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 are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0033] like Figure 1 As shown, according to an embodiment of the present invention, a laser-induced phase change radio frequency switch with an anti-reflection layer enhanced absorption of the present invention comprises: a laser light source a and a switch structure b; wherein the switch structure b comprises: an anti-reflection passivation layer 1, a phase change material layer 2, a metal electrode layer 3 and a dielectric substrate layer 4; in this embodiment, the phase change material layer 2 and the dielectric substrate layer 4 are arranged in sequence from top to bottom; the metal electrode layer 3 is connected to the dielectric substrate layer 4, and the metal electrode layer 3 is respectively arranged on two opposite sides of the periphery of the phase change material layer 2. In this embodiment, the phase change material layer 2 is located in the middle above the dielectric substrate layer 4, and the metal electrode layer 3 can be symmetrically arranged on two opposite sides of the phase change material layer 2; wherein the metal electrode layer 3 is connected to the phase change material layer 2 to form a microstrip line structure or a coplanar waveguide structure, so that the metal electrode layer 3 is a path for the input and output of the radio frequency signal of the phase change material layer 2. In this embodiment, the anti-reflection passivation layer 1 is located at the uppermost layer to completely cover the phase change material layer 2; wherein the anti-reflection passivation layer 1 is a light-transmitting layer, and the anti-reflection passivation layer 1 directly above the phase change material layer 2 serves as a light incident surface for incident laser light and an exit surface for reflected laser light. In this embodiment, the laser light source a is arranged opposite to the anti-reflection passivation layer 1 to induce the phase change of the phase change material layer 2 based on the anti-reflection effect of the anti-reflection passivation layer 1.

[0034] In another embodiment, the anti-reflection passivation layer 1 is used to cover the phase change material layer 2 and the position where the phase change material layer 2 is connected to the metal electrode layer 3. The metal electrode layer 3 is divided into two parts, the thickness of the metal electrode layer 3 in the first part is the same as the thickness of the phase change material layer 2, and the thickness of the metal electrode layer 3 in the second part is higher than the phase change material layer 2 and slightly overlaps the phase change material layer 2, thereby, the metal electrode layer 3 and the phase change material layer 2 form a concave structure with high sides and low in the middle; furthermore, the position where the phase change material layer 2 is connected to the metal electrode layer 3 is covered by the metal electrode layer 3, so that the anti-reflection passivation layer 1 forms a groove between the opposite metal electrode layer 3 and the phase change material layer 2, so as to accurately limit the position of the laser incident on the phase change material layer 2.

[0035] like Figure 1 As shown, according to one embodiment of the present invention, the anti-reflection passivation layer 1 is made of a transparent, insulating material and the melting point of the anti-reflection passivation layer 1 is greater than the phase change temperature of the phase change material layer 2; wherein the material used to prepare the anti-reflection passivation layer 1 is one or more of aluminum nitride, zinc sulfide, zinc selenide, magnesium fluoride, silicon nitride, silicon dioxide and titanium oxide.

[0036] like Figure 1 As shown, according to one embodiment of the present invention, the anti-reflection passivation layer 1 is a single-layer anti-reflection thin film layer; wherein, the anti-reflection passivation layer 1 uses a material with a refractive index between that of air and the phase change material layer 2, and by controlling the film thickness of the anti-reflection passivation layer 1, the reflected light from the air and the anti-reflection passivation layer 1 and the reflected light from the anti-reflection passivation layer 1 and the phase change material layer 2 are canceled to achieve an anti-reflection effect.

[0037] Through the above arrangement, the anti-reflection passivation layer 1 of the present invention can not only prevent the phase change material layer 2 from melting during the amorphization process, but also avoid the loss of laser energy, ensuring that the laser energy passes through the anti-reflection passivation layer 1 as losslessly as possible to irradiate the phase change material layer 2. In addition, the anti-reflection passivation layer 1 of the present invention can also effectively prevent the short circuit of the metal electrode layer 3 through the insulation arrangement, so as to ensure the stable and reliable operation of the entire switch.

[0038] In this embodiment, the thickness of the anti-reflection passivation layer 1 is less than or equal to 1 μm.

[0039] According to an embodiment of the present invention, the anti-reflection passivation layer 1 includes multiple anti-reflection thin film layers, and the refractive index of each anti-reflection thin film layer is different, so that the equivalent refractive index of the anti-reflection passivation layer 1 is between the air and the phase change material layer. In this embodiment, the anti-reflection passivation layer 1 is configured by setting the number of layers and thickness so that when the laser beam is incident on the anti-reflection passivation layer 1, a reflection occurs on the upper surface of the anti-reflection passivation layer 1 (i.e. Figure 2 R1), and after passing through the anti-reflection passivation layer 1, it is reflected again on the lower surface, and then refracted through the upper surface of the anti-reflection passivation layer 1 (i.e. Figure 2 R2), the subsequent multiple reflected laser energy is low and can be ignored, and the impact of the first reflection R1 and the second reflection R2 on the overall reflectivity is mainly considered. By controlling the refractive index and thickness of the anti-reflection passivation layer, the light intensities of the two reflected light beams R1 and R2 offset each other, and the total reflectivity is lower than the reflectivity of the phase change material layer, achieving the effect of reducing reflection. Among them, the closer the phase difference between the two beams of light is to an odd multiple of π, the better the anti-reflection effect.

[0040] In this embodiment, the refractive index of air is set as n0, the refractive index of the antireflection passivation layer 1 is n1, and the refractive index of the phase change material layer 2 is n2. Thus, when the antireflection passivation layer 1 is arranged as a single layer, by controlling the thickness d and the refractive index n1 of the antireflection passivation layer 1, the phase difference between the two reflected light beams is made equal to π, the light intensities of the two reflected light beams cancel each other out, and the total reflectance is lower than the reflectance of the phase change material layer, so that the energy of the reflected light is minimized, achieving the effect of reducing reflection. In this embodiment, the refractive index n1 of the antireflection passivation layer 1 should be between the refractive indices of air and the phase change material layer 2, that is, n0 < n1 < n2. When the refractive index n1 of the antireflection passivation layer 1 is closer to the square root of the product of the refractive index n0 of air and the refractive index n2 of the phase change material layer 2, the antireflection effect is more obvious. In another embodiment, if there is no suitable refractive index for setting the single-layer antireflection passivation layer 1, the antireflection passivation layer 1 can also adopt a multi-layer structure. The multi-layer antireflection passivation layer 1 adopts several uniform antireflection thin film layers with different refractive indices, that is, a non-uniform film with a variable refractive index. The refractive index of the entire antireflection layer changes continuously with the increase of the thickness. By artificial control, the refractive index of the multi-layer antireflection thin film layer is between the refractive indices of air and the phase change material layer 2, and when it is closer to the square root of the product of the refractive indices n0 and n2 of the phase change material layer 2, the antireflection effect is more obvious. It should be noted that since the refractive index difference between the crystalline and amorphous phase change material layers 2 is relatively large, the antireflection effects of the phase change material layer 2 in the two states need to be considered equally when designing the antireflection passivation layer 1. Compared with the crystallization process, amorphization requires a higher laser power. Therefore, the antireflection effect of the crystalline phase change material can be considered preferentially.

[0041] As Figure 1 shown, according to an embodiment of the present invention, the phase change material layer 2 is a phase change material layer having a resistivity ratio greater than 10 3 before and after phase change; wherein, the phase change material layer 2 can absorb laser energy to switch between the crystalline state and the amorphous state, realizing the switching between low resistivity and high resistivity, so as to realize the conduction and disconnection of the metal electrode layers 3 on the relative two sides. In this embodiment, the phase change material layer 2 is made of one or more of, including but not limited to, germanium telluride, germanium antimony telluride, vanadium dioxide, antimony selenide, and antimony telluride.

[0042] In this embodiment, the phase change RF switch utilizes the laser pulses of the laser light source a to generate heat, and heats the phase change material layer 2 to make it reach the phase change condition and undergo a phase change, thereby realizing the state switching of the phase change RF switch; wherein, the laser induction process of the phase change material layer 2 is mainly based on the photothermal effect of the laser on the substance. When the laser irradiates the surface of the phase change material layer 2, part of the light is reflected, and part of the light is irradiated into the phase change material layer 2. The laser irradiated into the phase change material layer 2 heats the phase change material layer 2. The phase change material layer 2 absorbs the laser energy and converts it into heat, causing the phase change material layer 2 to start heating up from the surface and gradually transfer to the interior of the phase change material layer 2. Therefore, the laser-induced phase change process of the phase change material layer 2 to produce a crystalline-amorphous phase change is closely related to the optical properties of the phase change material layer 2 itself. Figure 3 As shown, the phase change material layer 2 itself has a high reflectivity, especially the reflectivity of the crystalline phase change material layer 2 reaches more than 60%, resulting in a waste of most of the laser energy. For example, when the phase change material layer 2 is a germanium telluride layer, due to the metallic properties of the germanium telluride material, the reflectivity is as high as 70%, which is the main reason for the loss of laser energy. Then, an anti-reflection passivation layer 1 is added to the surface of the phase change material layer 2, and one or more materials are stacked to form a single or multi-layer anti-reflection layer. On the one hand, it acts as a passivation layer to protect the phase change material layer 2 from being oxidized; on the other hand, it acts as an anti-reflection layer to effectively reduce the reflectivity of the laser irradiated in the phase change material layer 2 area, increase the laser energy of the laser incident on the phase change material layer 2, thereby increasing the heat energy converted from the laser energy, improving the utilization rate of the laser energy, and finally reducing the energy threshold of the RF switch state switching.

[0043] like Figure 1 As shown, according to one embodiment of the present invention, the metal electrode layer 3 has an electrical conductivity greater than 1×10 7 S / m metal layer; in this embodiment, the metal electrode layer 3 is made of one or more materials including but not limited to gold, copper and silver.

[0044] Through the above arrangement, the metal electrode layer 3 is made of a material with an electrical conductivity greater than 1×10 7 The metal of S / m can effectively reduce the resistance loss on the metal electrode layer 3, so that the present invention has the advantage of low insertion loss.

[0045] like Figure 1 As shown, according to one embodiment of the present invention, the dielectric substrate layer 4 is made of one or more materials including but not limited to glass, silicon carbide, silicon, aluminum nitride and sapphire.

[0046] To further illustrate this solution, further examples are given.

[0047] Example 1

[0048] In this embodiment, the laser light source a selects green light with a wavelength of 532nm and a pulse width of 30ns, the dielectric base layer 4 uses a high-resistance silicon layer; the phase change material layer 2 uses a germanium telluride layer with a thickness of 100nm; the metal electrode layer 3 uses a gold layer with a thickness of 450nm; the anti-reflection passivation layer 1 uses a silicon dioxide layer with a thickness of 60nm.

[0049] Figure 4 and Figure 5 This is a curve showing the variation of the reflectivity with the laser wavelength after adding the anti-reflection passivation layer 1 of silicon dioxide in this example. Adding the anti-reflection passivation layer 1 can reduce the reflectivity of crystalline germanium telluride to 49% and the reflectivity of amorphous germanium telluride to 19%.

[0050] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0051] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser-induced phase change radio frequency switch with enhanced absorption of an anti-reflection layer, characterized in that: include: Laser light source (a) and switch structure (b); The switch structure (b) comprises: an anti-reflection passivation layer (1), a phase change material layer (2), a metal electrode layer (3) and a dielectric substrate layer (4); The metal electrode layer (3) and the phase change material layer (2) are arranged on the dielectric base layer (4), the phase change material layer (2) is located in the middle above the dielectric base layer (4), the metal electrode layer (3) is located at the periphery of the phase change material layer (2), and the anti-reflection passivation layer (1) is located at the uppermost layer so as to completely cover the phase change material layer (2); The anti-reflection passivation layer (1) is a light-transmitting layer, and the anti-reflection passivation layer (1) directly above the phase change material layer (2) serves as a light incident surface for incident laser light and an exit surface for reflected laser light; The laser light source (a) is arranged opposite to the anti-reflection passivation layer (1) so as to induce the phase change of the phase change material layer (2) based on the anti-reflection passivation layer (1).

2. The laser induced phase change radio frequency switch according to claim 1, characterized in that: The anti-reflection passivation layer (1) is made of a transparent, insulating material, and the melting point of the anti-reflection passivation layer (1) is greater than the phase change temperature of the phase change material layer (2); wherein the material used to prepare the anti-reflection passivation layer (1) is one or more of aluminum nitride, zinc sulfide, zinc selenide, magnesium fluoride, silicon nitride, silicon dioxide and titanium oxide.

3. The laser induced phase change radio frequency switch according to claim 2, characterized in that: The anti-reflection passivation layer (1) is a single-layer anti-reflection thin film layer; wherein the anti-reflection passivation layer (1) is made of a material with a refractive index between that of air and the phase change material layer (2), and by controlling the film thickness of the anti-reflection passivation layer (1), the reflected light from the air and the anti-reflection passivation layer (1) and the reflected light from the anti-reflection passivation layer (1) and the phase change material layer (2) are canceled out, thereby achieving an anti-reflection effect.

4. The laser induced phase change radio frequency switch according to claim 2, characterized in that: The anti-reflection passivation layer (1) comprises multiple anti-reflection thin film layers, and the refractive index of each anti-reflection thin film layer is different, so that the equivalent refractive index of the anti-reflection passivation layer (1) is between that of air and the phase change material layer.

5. The laser induced phase change radio frequency switch according to claim 1, characterized in that: The phase change material layer (2) has a resistivity ratio greater than 10 before and after the phase change. 3 Made of phase change material.

6. The laser induced phase change radio frequency switch according to claim 5, characterized in that: The phase change material layer (2) is made of one or more of germanium telluride, germanium antimony telluride, vanadium dioxide, antimony selenide and antimony telluride.

7. The laser induced phase change radio frequency switch according to claim 6, characterized in that: The metal electrode layer (3) is an input and output channel for radio frequency signals, and its conductivity is greater than 1×10 7 S / m metal layer.

8. The laser induced phase change radio frequency switch according to claim 7, characterized in that: The metal electrode layer (3) is made of one or more materials selected from the group consisting of gold, copper and silver; The dielectric substrate layer (4) is made of one or more materials selected from the group consisting of glass, silicon carbide, silicon, aluminum nitride and sapphire.

9. The laser induced phase change radio frequency switch according to claim 8, characterized in that: The thickness of the anti-reflection passivation layer (1) is less than or equal to 1 μm.

10. The laser induced phase change radio frequency switch according to claim 8, characterized in that: The laser light source (a) is used to generate laser light with a wavelength of 100nm-2000nm; The irradiation range of the laser light source (a) covers the phase change material layer (2).

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