Phase change material electro-optical modulation device based on transparent micro-heater and preparation thereof

Abstract

The application discloses a phase change material electro-optical modulator based on a transparent micro-heater and a manufacturing method thereof. The device comprises a bottom layer, a support layer, an electrode layer and a phase change layer. The middle region of the substrate layer is suspended. The electrode layer comprises a transparent electrode layer in the middle region and metal electrode layers arranged on both sides. The phase change layer covers the space above the transparent electrode layer and is provided with a plurality of phase change material nanodisks. A metal cap is arranged above each phase change material nanodisk. The device of the application inputs voltage to the metal electrode layers on both sides through an external power supply, so that the transparent electrode layer generates Joule heat when electrified, drives the phase change layer in the space above to change phase, and makes the optical dielectric constant of the phase change layer change significantly, thereby realizing dynamic regulation and control of the transmission light in the middle infrared wave band.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electro-optical modulation, and particularly to a phase change material electro-optical modulator based on a transparent micro-heater and a manufacturing method thereof. BACKGROUND

[0002] Phase change materials can produce significant changes in their electrical and optical properties through reversible switching between amorphous and crystalline states, which provides a new idea for designing reconfigurable electro-optical modulation devices. Among the tunable and active materials, phase change materials have unique properties such as non-volatility, CMOS compatibility, scalability, and ultrafast switching. Therefore, the combination of phase change materials and the structural design of micro-nano photonic devices will greatly improve the performance and device integration of existing electro-optical modulation devices.

[0003] The compound GST, composed of Ge, Sb, and Te elements in a certain proportion, is a typical thermally induced phase change material. Its characteristics are that any way that can generate high temperature can actually cause GST phase change, and after phase change, it can maintain stable crystalline state without the need for external energy to maintain the phase state of the material. GST has multiple different element composition ratios, and there are certain property differences between them. Among them, Ge2Sb2Te5 has more excellent performance in phase change speed and ductility than other element ratio compounds, and is the most widely used material in electro-optical modulator devices and phase change material metasurfaces. According to previous literature reports, currently, three ways are commonly used to control the phase state of Ge2Sb2Te5, namely direct heating, pulsed laser irradiation, and voltage pulse. The advantages and disadvantages of these three methods are obvious, and their application scenarios are different. Direct heating with a hot plate or other equipment is the most direct and convenient way to achieve large-area phase change of the material in a short time. However, due to the inability of the hot plate to provide the heat required for rapid annealing in a short time, it cannot achieve reversible switching of the phase state of Ge2Sb2Te5 and control of the phase change degree, and it is difficult to complete the phase state control of the local area material. Compared with direct heating, pulsed laser irradiation has the advantages of fast switching, stable control, reversible switching of the material, and control of the phase state of the local area, but this method has great limitations in practical application scenarios, requiring the construction of a large laser equipment and a complex optical system. The voltage pulse method is the fastest and most convenient, which can arbitrarily switch the phase state of the material by applying voltage to the electrode layer of the electrically driven platform with an external power supply. In 2021, Yifei Zhang et al. designed a large-scale, electrically reconfigurable non-volatile metasurface platform based on optical phase change materials. The device uses the unique optical phase change material Ge2Sb2Se4Te (GSST) to demonstrate its huge non-volatile refractive index modulation capability, wideband low light loss, and large reversible switching volume, which significantly enhances the light-matter interaction in active optical phase change material media (see literature: Nature Nanotechnology 2021, 661, 666.); In 2022, Sajjad et al. proposed a kind of in-situ electrically driven tunable metasurface based on the difference in optical properties before and after the phase change of GST-225, to realize non-volatile, reversible, multi-level, fast and significant optical modulation in the near-infrared spectral range. The efficiency of the electrically driven reconfigurable metasurface reaches 80%, and it has more than 250 nm of quasi-continuous spectral tuning capability (see literature: Nature Communications 2022, 13, 1696.). However, both of the above methods will have the phenomenon of filament formation during power-on, that is, the fine line formed by the first crystallization will prevent the crystallization of the surrounding material, thereby affecting the uniform crystallization of the entire region.The "filament effect" prevents the phase state switching of the current directly passing through the phase change material in the electro-optical modulation device, thereby affecting the performance of the device. In order to solve the problem of "filament effect", the micro-heater is currently applied to the electric driving platform to further overcome the filament phenomenon generated in the process of applying electricity to the phase change material. However, the traditional micro-heater usually uses high-reflective metal as a thermal resistance layer, which limits the phase change material optical modulator integrated with the micro-heater to work in the reflective mode in the mid-infrared to terahertz wave band. In addition, the power consumption of the voltage pulse is high, and most of the heat of the micro-heater is dissipated to the substrate, which further hinders the integration of the phase change material optical modulator with the reconfigurable micro-optical chip system. The prior art consists of a substrate layer and a cover layer, and there is a space between the cover layer and the substrate layer, and a plurality of gold nanodisks are arranged in the space, and a phase change material is arranged on each gold nanodisk. The cover layer covers the phase change material and serves as a light field regulation unit of the device, and metal electrodes are arranged on both sides of the cover layer and serve as electrode regulation units of the device. By applying an external voltage to make the cover layer continuously generate Joule heat to drive the phase change material to change phase, the optical dielectric constant of the phase change material changes significantly, thereby realizing dynamic electro-optical modulation of mid-infrared wave band light; the device uses two-dimensional semi-metallic material PtSe2 as the cover layer, which has the advantages of high light transmission, good electrical conductivity, realizing a maximum modulation depth of about 64.8% of reflected light, and being capable of dynamically regulating spatial incident light, but still has the problems of low modulation depth of transmitted light, uneven heating and high heat loss. SUMMARY

[0004] The present application is to overcome the problems of low modulation depth of transmitted light, uneven heating and high heat loss of the prior art electro-optical modulation device, and to provide a phase change material electro-optical modulation device based on a transparent micro-heater and a manufacturing method thereof.

[0005] To achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0006] A phase change material electro-optical modulation device based on a transparent micro-heater, comprising a substrate layer, a support layer, an electrode layer and a phase change layer; a through hole is arranged in the middle of the substrate layer; the support layer is located on the upper surface of the substrate layer; the electrode layer is located on the upper surface of the support layer and comprises a transparent electrode and metal electrodes at both ends of the transparent electrode; the phase change layer is located on the upper surface of the transparent electrode; a metal cap is arranged on the upper surface of the phase change layer; and a metal layer is arranged on the upper surface of the transparent electrode.

[0007] In the present application, the substrate layer is a silicon layer, a through hole is opened in the middle of the substrate layer, and the support layer is located on the upper surface of the substrate layer and covers the through hole; the support layer comprises a silicon nitride layer and a silicon oxide layer, is transparent in the ultraviolet to far infrared wave band, can withstand high stress, plays a good supporting role, and can balance the stress generated during the heating of the silicon nitride. Preferably, the upper surface area of the through hole is 0.3-0.4% of the upper surface area of the substrate layer, for example, the upper surface area of the through hole is 600*600 μm, and the upper surface area of the substrate layer is 10*10 mm; the thickness of the silicon nitride layer is 200 nm, and the thickness of the silicon oxide layer is 300 nm; the silicon oxide layer is located on the upper surface of the silicon nitride layer.

[0008] In the present application, the transparent electrode layer is a transparent conductive oxide film layer, preferably an ITO film layer; the thickness of the transparent electrode layer is 300 nm, the upper surface area of the transparent electrode layer is 2-3% of the upper surface area of the through hole, and the transparent electrode is entirely above the through hole.

[0009] In the present application, the material of the phase change layer is Ge2Sb2Te5, and the phase change layer is a nano disc array structure of phase change material; preferably, the shape of the nano disc of phase change material is cylindrical, the diameter is 260 nm, the height is 100-200 nm, and the spacing of the nano disc of phase change material is 200-300 nm; by designing the structural parameters of the nano disc of phase change material, the best modulation capability for spatial light can be obtained.

[0010] In the present application, the metal electrode is a gold electrode; the metal cap is a gold cap; and the metal layer is a gold layer. Preferably, the shape of the metal cap is the same as that of the nano disc of phase change material, the diameter of the metal cap is the same as that of the nano disc of phase change material, and the thickness of the metal cap is the same as the thickness of the gold electrode layer and the metal layer; by using a well-designed shadow mask to deposit together with the gold electrode layer and the metal layer, the metal cap is attached directly above the nano disc of phase change material, the interaction between spatial light and the phase change material is enhanced, and stronger local resonance is generated.

[0011] The present application discloses a preparation method of a phase change material electro-optical modulation device based on a transparent micro-heater, comprising the following steps:

[0012] (1) preparing a support layer on a substrate layer, and then opening a through hole in the middle of the substrate layer;

[0013] (2) preparing a transparent electrode layer on the support layer, and then preparing a phase change layer on the transparent electrode layer;

[0014] (3) preparing a metal film on the support layer, the transparent electrode layer and the phase change layer to form a metal electrode and a metal cap and a metal layer.

[0015] In the present application, the support layer is prepared by electron beam evaporation. Preferably, the support layer of silicon nitride film is prepared above the substrate layer by electron beam evaporation, then a transparent window is etched in the center area of the substrate by a wet etching method (i.e. a through hole is prepared below the silicon nitride film), and then a silicon oxide film is prepared on the silicon nitride film by electron beam evaporation.

[0016] In the present application, the transparent electrode layer is prepared by ion beam sputtering deposition; the phase change layer is prepared by ion beam sputtering deposition; and the metal film is prepared by electron beam evaporation to form a metal electrode and a metal cap and a metal layer.

[0017] The phase change material electro-optical modulation device based on the transparent micro-heater has high thermal conductivity, better temperature uniformity, is transparent in the near-infrared to mid-infrared wave band, has good electrical conductivity, high light transmittance, high melting point and is easy to prepare, can exist stably in the environment for a long time, improves the stability of heating, reduces the loss of incident light, has high electrical conductivity, good stability and is not easy to oxidize, and can reduce the input voltage of the device and improve the stability of the device.

[0018] The method for manufacturing the phase change material electro-optical modulation device based on the transparent micro-heater is suitable for manufacturing the phase change material electro-optical modulation device based on the transparent micro-heater, which is composed of a substrate layer, a support layer, an electrode layer and a phase change layer and the like. The intermediate area of the MEMS micro-heater is suspended and transparent, and a mid-infrared electro-optical modulation device with an ITO / Ge2Sb2Te5 / Au three-layer stacked structure is prepared. The incident light interacts with the Ge2Sb2Te5 nanodisk to form plasmonic resonance, the metal cap at the top further enhances the local resonance, the voltage is input through the gold electrodes on both sides, the transparent electrode ITO with high impedance in the center area generates Joule heat, the phase change of the nanodisk array of the phase change material above is triggered to cause a significant change in the optical dielectric constant, and thus the dynamic electro-optical regulation of the on-off state of the transmitted light of the device is realized.

[0019] Therefore, the present application has the following beneficial effects: the device of the present application adopts the wet etching method to prepare the suspended thin-film micro-heater, has the characteristics of high heating efficiency, fast response time and good mechanical stability; the ITO electrode is transparent in the mid-infrared wave band, reduces the loss of incident light, and the high impedance can generate higher heat during the heating process; the phase state of the nanodisk of the phase change material is adjusted by the voltage, which can not only rapidly and reversibly switch between the amorphous state and the crystalline state, but also dynamically regulate the on-off state of the incident light in the mid-infrared wave band. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structure unit section view of the phase change material electro-optical modulation device of the present application.

[0021] Figure 2is the structure unit top view of the phase change material electro-optical modulation device of the present application.

[0022] Figure 3 is the Ge2Sb2Te5 nanodisk array top view of the phase change material electro-optical modulation device of the present application.

[0023] Figure 4 is the phase change schematic diagram of the phase change material electro-optical modulation device of the present application.

[0024] Figure 5 is the temperature distribution schematic diagram of the analog phase change material electro-optical modulation device of the present application under 2V input voltage for 100µs.

[0025] Figure 6 is the manufacturing flow chart of the phase change material electro-optical modulation device of the present application.

[0026] Figure 7 is the transmission spectrum diagram of the analog phase change material electro-optical modulation device of the present application in the infrared wavelength range in the crystalline state and amorphous state.

[0027] Figure 8 is the reflection spectrum diagram of the analog phase change material electro-optical modulation device of the present application in the infrared wavelength range in the crystalline state and amorphous state

[0028] Figure 9 is the transmission spectrum comparison diagram of the analog phase change material electro-optical modulation device of the present application in the infrared wavelength range in the crystalline state and amorphous state using different phase change material nanodisk heights

[0029] Figure 10 is the modulation depth comparison diagram of the analog phase change material electro-optical modulation device of the present application in the infrared wavelength range in the crystalline state and amorphous state using different phase change material nanodisk heights.

[0030] In the figure: 1, substrate; 2, support layer; 3, transparent electrode layer; 4, gold electrode layer; 5, phase change material nanodisk; 6, metal cap; 11, metal layer; 12, via hole; a, amorphous state; c, crystalline state. DETAILED DESCRIPTION

[0031] The application discloses a phase change material electro-optical modulation device based on a transparent micro-heater, which adopts a micro-heater to induce phase change of a phase change material to perform electro-optical modulation; the electro-optical modulation device comprises a substrate layer, a support layer, an electrode layer and a phase change layer; the material of the substrate layer is silicon, and a middle region of the substrate layer is suspended (a through hole); the material of the support layer is silicon nitride and silicon oxide; the electrode layer comprises a transparent electrode layer and a metal electrode layer arranged on two sides; the phase change layer covers a space above the transparent electrode layer and is provided with a plurality of phase change material nanodisks; a metal cap is arranged above each phase change material nanodisk; a metal layer is arranged on the upper surface of the transparent electrode layer, that is, the metal layer and the phase change layer jointly cover the upper surface of the transparent electrode; wherein the electrode layer serves as an electrode and a light field regulation unit of the device; an external power supply inputs voltage to the metal electrode layers on the two sides, so that the transparent electrode layer generates Joule heat to drive the phase change layer in the space above to change phase, so that the optical dielectric constant of the phase change layer changes significantly, and thus dynamic regulation and control of transmission light in a middle infrared wave band is realized.

[0032] The application discloses a suspended thin film heater made on a substrate, which has the advantages of high heating efficiency, low heat loss and fast response time, and the suspended thin film design improves the heating efficiency of the micro-heater and enables the micro-heater to work in a transmission mode.

[0033] In the application, the thickness of the silicon substrate layer is 400 µm, the length and width are 10×10 mm, the suspended region is prepared by a back wet etching method, the thickness is 400 µm, and the length and width are 600×600 µm, which is a through hole structure. The thickness of the silicon nitride support layer is 200 nm, and the thickness of the silicon oxide is 300 nm. The silicon nitride support layer is transparent in the ultraviolet to far infrared wave band and can withstand high stress, thereby playing a good supporting role and balancing the stress generated in the heating process of the silicon nitride.

[0034] In the application, the material of the transparent electrode layer is an ITO thin film of transparent conductive oxide, the thickness of the transparent electrode layer is 300 nm, and the length and width are 100×100 µm; the material of the phase change layer is Ge2Sb2Te5, the phase change layer is provided with a plurality of phase change material nanodisks, the shape of the phase change material nanodisks is circular, the diameter is 260 nm, and the height is 100-200 nm. The spacing of the phase change material nanodisks is 200-300 nm, and the best modulation capacity of spatial light can be obtained by optimizing the structural parameters of the phase change material nanodisks; the material of the metal layer is gold, the material of the metal electrode layer is gold, the material of the metal cap is gold, the shape of the metal cap is the same as that of the phase change material nanodisk, the diameter of the metal cap is the same as that of the phase change material nanodisk, the thickness of the metal cap is the same as that of the gold electrode layer and the metal layer, the metal cap is deposited on the top of the phase change material nanodisk by using a well-designed shadow mask together with the gold electrode layer, and the spatial light and the phase change material are enhanced to interact with each other and generate stronger local resonance.

[0035] The application discloses a preparation method of the phase change material electro-optical modulation device based on the transparent micro-heater.

[0036] (1) a silicon nitride film is prepared on the substrate layer by electron beam evaporation;

[0037] (2) a transparent window is etched in the center area of the back of the substrate by a wet etching method;

[0038] (3) a silicon oxide film is prepared on the silicon nitride film by electron beam evaporation;

[0039] (4) a transparent electrode layer with a lateral size of 100*100 mu m is deposited by using a shadow mask and an ion beam sputtering deposition method;

[0040] (5) ZEP photoresist is spin-coated on the transparent electrode layer by using a spin coater;

[0041] (6) the photoresist is exposed to an electron beam and developed;

[0042] (7) phase change material Ge2Sb2Te5 is deposited on the ZEP photoresist by using an ion beam sputtering method, and the residual photoresist is removed by a stripping technology, so that a Ge2Sb2Te5 nanodisk array is obtained;

[0043] (8) a gold electrode, a metal cap above the Ge2Sb2Te5 nanodisk array and a metal layer between the nanodisk array are deposited by using a shadow mask and an electron beam evaporation method.

[0044] The prior art discloses an electro-optical modulation device based on a micro electric heater and a manufacturing method thereof, the device is composed of a substrate layer and a cover layer, a space exists between the cover layer and the substrate layer, a plurality of gold nanodisks are arranged in the space, and phase change material is arranged on each gold nanodisk. The cover layer covers the phase change material and serves as a light field regulation unit of the device, metal electrodes are arranged on the two sides of the cover layer and serve as electrode regulation units of the device; the device adopts two-dimensional semi-metal material PtSe2 as the cover layer, has the advantages of high light transmission, good electrical conductivity, a maximum modulation depth of about 64.8% on reflected light, dynamic regulation on spatial incident light and the like, but still has the problems of being unable to modulate transmitted light and being able to only reduce the filament phenomenon by adjusting the structure and size of the device. The device of the application can realize a maximum modulation depth of about 71.6% on transmitted light by adopting a center-opening micro heater to regulate the phase change material device, and can concentrate the electric Joule heat generated when powered on on the support layer above the through hole, thereby increasing the stability and uniformity of heating, which makes the phase change material crystallize more uniformly in the phase change process, thereby reducing the filament phenomenon.

[0045] The present application is further described below in conjunction with the accompanying drawings and specific embodiments. The raw materials used in the present application are all existing products, and the specific preparation operations and performance tests are conventional techniques. Example 1

[0046] Referring to Figure 1 As shown in the structure profile of the phase change material electro-optical modulation device based on transparent micro-heater, it includes a substrate layer 1, a support layer 2, a transparent electrode layer 3, a gold electrode layer 4 and a phase change layer 5. The material of the substrate layer 1 is silicon, the thickness is 400 µm, the length and width are 10×10 mm, and the silicon at the back of the center area is etched by wet etching to form a through-hole structure 12 (the thickness is 400 µm, the length and width are 600×600 µm), so that the support layer 2 above the center area of the substrate layer 1 is suspended; the material of the support layer 2 is silicon nitride and silicon oxide, the thickness of the silicon nitride is 200 nm, and the thickness of the silicon oxide is 300 nm; the material of the transparent electrode layer 3 is ITO, which is located directly above the center area of the support layer 2, the thickness is 300 nm, the length and width are 100×100 µm, and the transparent electrode layer 3 is flanked by the gold electrode layer 4, the thickness of the gold electrode layer 4 is 100 nm; a plurality of phase change material nanodisks 5 and a metal layer 11 are provided above the transparent electrode layer 3, the shape of the phase change material nanodisk 5 is circular, the material is phase change material Ge2Sb2Te5, all the phase change material nanodisks 5 form a Ge2Sb2Te5 nanocolumn array, the diameter of the phase change material nanodisk 5 is 260 nm, the height is 150 nm, and the spacing of the nanodisks is 200 nm; the metal cap 6 has the same shape as the phase change material nanodisk 5, covers directly above the phase change material nanodisk 5, and the thickness is 100 nm; the metal film between the nanodisk array forms a metal layer.

[0047] Referring to Figure 2 As shown in the structure profile of the phase change material electro-optical modulation device based on transparent micro-heater, it includes a substrate layer 1, a support layer 2, a transparent electrode layer 3, a gold electrode layer 4 and a phase change layer 5. The material of the substrate layer 1 is silicon, the thickness is 400 µm, the length and width are 10×10 mm, and the silicon at the back of the center area is etched by wet etching to form a through-hole structure 12 (the thickness is 400 µm, the length and width are 600×600 µm), so that the support layer 2 above the center area of the substrate layer 1 is suspended; the material of the support layer 2 is silicon nitride and silicon oxide, the thickness of the silicon nitride is 200 nm, and the thickness of the silicon oxide is 300 nm; the material of the transparent electrode layer 3 is ITO, which is located directly above the center area of the support layer 2, the thickness is 300 nm, the length and width are 100×100 µm, and the transparent electrode layer 3 is flanked by the gold electrode layer 4, the thickness of the gold electrode layer 4 is 100 nm; a plurality of phase change material nanodisks 5 and a metal layer 11 are provided above the transparent electrode layer 3, the shape of the phase change material nanodisk 5 is circular, the material is phase change material Ge2Sb2Te5, all the phase change material nanodisks 5 form a Ge2Sb2Te5 nanocolumn array, the diameter of the phase change material nanodisk 5 is 260 nm, the height is 150 nm, and the spacing of the nanodisks is 200 nm; the metal cap 6 has the same shape as the phase change material nanodisk 5, covers directly above the phase change material nanodisk 5, and the thickness is 100 nm; the metal film between the nanodisk array forms a metal layer.

[0048] Referring to Figure 3 Figure 1 shows a top view of a Ge2Sb2Te5 nanodisk array of a phase-change material electro-optical modulation device based on transparent micro-heater, the Ge2Sb2Te5 nanodisk array is composed of all phase-change material nanodisks 5, located directly above the transparent electrode layer 3, obtained by electron beam exposure, ion beam sputtering and stripping technology.

[0049] Referring to Figure 4 Figure 2 shows a phase-change schematic diagram of a phase-change material electro-optical modulation device based on transparent micro-heater, by applying voltage to the gold electrode layer 4 externally, due to the impedance of the transparent electrode layer 3 being much higher than that of the gold electrode layer 4, the electric Joule heat generated during power-on is concentrated in the transparent electrode layer 3, causing the phase-change material nanodisks 5 above it to change phase, and the optical dielectric constant to change significantly, thereby achieving dynamic regulation of the mid-infrared light incident in space.

[0050] Referring to Figure 5 Figure 3 shows the temperature distribution diagram of the transparent micro-heater when an input voltage of 2V is applied, obtained by electro-thermal simulation calculation using the finite element multi-physical field analysis method (COMSOL). From the results of electro-thermal simulation calculation, the design of the suspended thin film reduces the diffusion of heat to the substrate, and the temperature of the central region of the transparent electrode layer 3 reaches an average of 600K within 100us of power-on, far exceeding the phase-change temperature of Ge2Sb2Te5.

[0051] Referring to Figure 6 Figure 4 shows the specific manufacturing steps of a phase-change material electro-optical modulation device based on transparent micro-heater, as follows:

[0052] (1) Use electron beam evaporation to prepare a silicon nitride film support layer above the substrate layer;

[0053] (2) Etch a transparent window in the center of the back of the substrate by wet etching method;

[0054] (3) Use electron beam evaporation to prepare a silicon oxide film on the silicon nitride film;

[0055] (4) Use a shadow mask and ion beam sputtering to deposit a transparent electrode layer with a lateral size of 100x100µm;

[0056] (5) Use a spin coater to spin coat ZEP photoresist on the transparent electrode layer, at a speed of 3000r / min, and the baking temperature is 120℃;

[0057] (6) Expose the pattern by electron beam exposure and develop it;

[0058] (7) Use ion beam sputtering to deposit phase-change material Ge2Sb2Te5 on the ZEP photoresist, and then remove the residual photoresist by stripping technology to obtain a Ge2Sb2Te5 nanodisk array;

[0059] (8) Gold electrodes and metal caps above the Ge2Sb2Te5 nanodisk array and metal layers between the nanodisk arrays are deposited using a shadow mask and electron beam evaporation.

[0060] See Figure 7 and Figure 8 The figures show the transmission and reflection spectra of Ge2Sb2Te5 before and after the phase transition in the mid-infrared wavelength range, obtained by simulation calculation using the finite-difference time-domain (FDTD) method. Optimizing the structural dimensions achieves optimal impedance matching, enhancing the resonance peak generated during local electric field resonance within the device. By applying an external voltage to the electrodes to induce a phase transition in Ge2Sb2Te5, its optical dielectric constant is altered, allowing for active tuning of the transmitted light resonance wavelength. Simulation results show that when Ge2Sb2Te5 is in a completely amorphous state, it reaches its maximum transmission peak at a wavelength of 2.26 µm, with a transmittance of 71.63%. However, when Ge2Sb2Te5 is in a completely crystalline state, the extinction coefficient K increases significantly, equivalent to that of a metal, and the transmittance approaches 0 at a wavelength of 2.26 µm, almost completely blocking light transmission. The maximum modulation depth is 71.60%, at which point the transmittance peak redshifts to a wavelength of 3.41 µm, and the transmittance decreases to 10.54%. The redshift of the transmission peak before and after the phase transition indicates that the effective dielectric constant changes significantly due to the phase transition, the resonance peak value decreases significantly, and the resonance wavelength undergoes a significant redshift.

[0061] Following the above preparation method, different devices were obtained by changing the parameters of the phase change material nanodisks (height 100-200 nm). See also... Figure 9 and Figure 10 The figures show a comparison of transmission spectra and modulation depths in the infrared wavelength range for crystalline and amorphous Ge2Sb2Te5 nanodisks with different phase change material (PCM) heights. As the height of the PCM nanodisks increases from 100 nm to 200 nm, the maximum modulation depth increases from 26.76% to 71.60%, a significant blue shift occurs in the resonance wavelength, and there are significant differences in modulation depth. While increasing the height of the PCM nanodisks increases the difficulty of exfoliation during fabrication, it also enhances the plasmon resonance formed between the incident light and the PCM nanodisks, further increasing the switching amplitude of the transmitted light.

[0062] The application discloses a middle infrared electro-optical modulation device based on a transparent micro-heater and a manufacturing method thereof, and the device is composed of a silicon substrate, a silicon nitride and a silicon oxide supporting layer, an ITO transparent electrode layer, a gold electrode layer, a phase change material nanodisk array, a gold cap and the like multi-layer composite structure; the middle infrared electro-optical modulation device with a suspended transparent micro-heater in a central region and an ITO / Ge2Sb2Te5 / Au three-layer stack structure is prepared, the suspended thin film design can reduce the heat diffusion to the substrate, improve the stability of heating, the incident light interacts with the Ge2Sb2Te5 nanodisk to form plasmonic resonance, the metal cap at the top further enhances the local surface plasmon resonance, the voltage is input through the gold electrode layer on both sides, the transparent electrode layer with high impedance in the central region generates Joule heat, the phase change of the phase change material nanodisk above is triggered to make the optical dielectric constant change significantly, and thus the dynamic electro-optical regulation and control on the transmission light on-off state of the device is carried out. The micro-heater with the central region suspended is prepared by the back wet etching method, and the heat diffusion to the substrate region is greatly reduced; the volume and arrangement mode of the transparent electrode and the metal electrode are optimized, the stability and uniformity of heating are improved, the phase change of the Ge2Sb2Te5 nanodisk array is more uniform and stable when electrified, and the wire drawing phenomenon is almost avoided. The device related to the application can work in the middle infrared waveband of 2-5um, when the height of the Ge2Sb2Te5 nanodisk array is 200nm, the transmittance of Ge2Sb2Te5 is 71.63% at the wavelength of 2.26um when Ge2Sb2Te5 is in an amorphous state, the transmittance is close to 0 when Ge2Sb2Te5 is in a crystalline state, the maximum modulation depth of the transmission light can reach 71.6%, the extinction ratio reaches 204, and the dynamic regulation and control on the on-off state of the middle infrared waveband incident light is realized.

[0063] The specific embodiments described herein represent merely examples of the principles of this application. Various modifications or changes in addition or substitution to the described specific embodiments can occur to those skilled in the art upon reading the foregoing description. Such modifications or changes, however, should not be construed as a departure from the spirit and scope of the application, as set forth in the appended claims.

[0064] Although the terms such as phase change layer, supporting layer, covering layer and metal cap are used frequently herein, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the application; any interpretation of them as any kind of additional limitation is contrary to the spirit of the application.

Claims

1. A transparent micro-heater based phase change material electro-optical modulation device, comprising a substrate layer, a support layer, an electrode layer and a phase change layer; the substrate layer is provided with a through hole in the middle; the support layer is located on the upper surface of the substrate layer; the electrode layer is located on the upper surface of the support layer, comprising a transparent electrode and metal electrodes at both ends of the transparent electrode; the phase change layer is located on the upper surface of the transparent electrode; the upper surface of the phase change layer is provided with a metal cap; the upper surface of the transparent electrode is provided with a metal layer; the transparent electrode is entirely above the through hole; the phase change layer is a phase change material nanodisk array structure; the metal layer is arranged at the interval of the nanostructure in the nanodisk array.

2. The phase change material electro-optical modulator based on transparent micro-heater according to claim 1, wherein, The substrate layer is a silicon layer; the support layer comprises a silicon nitride layer and a silicon oxide layer; the transparent electrode is entirely above the through hole.

3. The phase change material electro-optic modulator device based on transparent micro-heater of claim 1, wherein, The transparent electrode layer is a transparent conductive oxide film layer; the material of the phase change layer is Ge2Sb2Te5; the phase change layer is a phase change material nanodisk array structure.

4. The phase change material electro-optical modulator based on transparent micro-heater according to claim 3, wherein, In the phase change material nanodisk array structure, the shape of the phase change material nanodisk is cylindrical, the height is 100-200 nm, and the interval of the phase change material nanodisk is 200-300 nm.

5. The phase change material electro-optic modulator device based on transparent micro-heater of claim 1, wherein, The metal electrode is a gold electrode; the metal cap is a gold cap; and the metal layer is a gold layer.

6. The method of making a transparent microheater based phase change material electro- optical modulator device of claim 1 comprising the steps of: (1) a support layer is prepared on the substrate layer, and then a through hole is opened in the middle of the substrate layer; (2) a transparent electrode layer is prepared on the support layer; then a phase change layer is prepared on the transparent electrode layer; (3) a metal film is prepared on the support layer, the transparent electrode layer and the phase change layer, to form a metal electrode and a metal cap and a metal layer.

7. The method of claim 6, wherein the transparent microheater is formed by a process comprising: depositing a first layer of a transparent conductive material on a substrate; depositing a second layer of a transparent conductive material on the first layer; and depositing a third layer of a transparent conductive material on the second layer. The support layer is prepared by electron beam evaporation; the transparent electrode layer is prepared by ion beam sputtering deposition; the phase change layer is prepared by ion beam sputtering deposition; and the metal film is prepared by electron beam evaporation, to form a metal electrode and a metal cap and a metal layer.

8. The method of claim 6, wherein the transparent microheater is formed by a process comprising: depositing a first layer of a transparent conductive material on a substrate; depositing a second layer of a transparent conductive material on the first layer; and depositing a third layer of a transparent conductive material on the second layer. The support layer is prepared by electron beam evaporation on the substrate layer, then a transparent window is etched in the central region of the substrate by a wet etching method, and then a silicon oxide film is prepared on the silicon nitride film by electron beam evaporation.

9. Use of the transparent micro-heater based phase change material electro-optical modulation device according to claim 1 in the preparation of an optical modulation device.

10. The method of electro-optical modulation of the phase change material electro- optical modulator based on transparent microheater according to claim 1, characterized in that, An input voltage is applied to the electrode layer to generate Joule heat in the transparent electrode, to trigger phase change of the phase change layer above, to cause changes in the optical dielectric constant, and to dynamically and optically control the on-off state of the transmitted light of the device.

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