Phase change photosynaptic device array and preparation method thereof

Abstract

The invention belongs to the technical field of integrated photoelectronics, and discloses a phase change photosynaptic device array and a preparation method thereof. The synaptic device array is of a cross array structure formed by a plurality of phase-change optical synaptic cells through directional couplers with the same number, an arc waveguide in each phase-change optical synaptic cell comprises a phase-change waveguide section, a heating layer is arranged above a phase-change material layer, and an isolating layer is arranged between a metal electrode and the waveguide. According to the synaptic device array, current joule heat generated by the heating layer under the action of electric pulses is transmitted to the phase-change material layer, so that the state of the phase-change material layer is changed, meanwhile, the isolation layer is used for shielding absorption and interference of the metal electrode on optical signals in the waveguide, and the optical loss of the array is reduced; therefore, the problem of heating structure integration of the phase-change photosynaptic device array can be effectively solved, and effective modulation of the phase-change photosynaptic device array is realized.

Description

Technical Field

[0001] The present invention belongs to the field of integrated optoelectronic technology, and more specifically, relates to a phase-change optical synapse device array and a preparation method thereof. Background Art

[0002] With the rapid development of big data and artificial intelligence, data transmission, calculation and storage have become new challenges in the current information field. The emergence of storage walls in the traditional von Neumann architecture has led researchers to shift their focus to brain-like computing. The human brain is composed of a large number of neurons and synapses. The neural network composed of neurons and synapses is the basis for the brain to process external information. Among them, synapses, as an important unit for information transmission between neurons, are a key component of the neural network. However, traditional optical synaptic devices are mainly based on carrier dispersion effects or thermo-optical effects, with high static power consumption and small modulation range. Therefore, it is of great significance to study new optical synaptic devices.

[0003] In recent years, phase change materials have attracted extensive attention from scholars at home and abroad due to their huge difference in optical constants between the two phases (refractive index change > 1) and the non-volatile multiple stable intermediate phases between the crystalline and amorphous states. Phase change optical synaptic devices have made some relatively good progress. However, in practical applications, neural networks contain large-scale synaptic arrays, but there are relatively few studies based on phase change optical synaptic arrays, and they are still at the single device stage. From synaptic single devices to array realization, many complex factors need to be considered, such as the process error between the array architecture design and the actual processing technology, and the integration between the heating structure and the computing unit. The existing phase change optical synaptic array directly applies the heating structure of a single device to the array unit, and the addressing complexity of the device array is high and the resource utilization is low. Therefore, the design of phase change optical synaptic device arrays and their adapted heating structures is an urgent problem to be solved. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a phase change optical synapse device, a preparation method and a phase change optical synapse device array, the purpose of which is to provide a heating layer above the phase change material layer in the phase change optical synapse device array and an isolation layer between the metal electrode and the waveguide, thereby solving the technical problem that the prior art is difficult to complete the effective modulation of the phase change optical synapse device array in the integration of the phase change optical synapse device array and the heating structure.

[0005] To achieve the above object, according to one aspect of the present invention, a phase change optical synapse device array is provided, which is a cross array structure formed by a plurality of phase change optical synapse units through the same number of directional couplers; each of the phase change optical synapse units includes an arc waveguide and a cross waveguide, and the arc waveguide includes an input section, an output section, and a phase change waveguide section arranged between the input section and the output section, so that the optical signal of the input section is coupled into the transverse waveguide of the cross waveguide, and the optical signal after the action of the phase change waveguide section is coupled out from the output section to the longitudinal waveguide of the cross waveguide; wherein the phase change waveguide section includes:

[0006] A substrate and a waveguide layer are arranged sequentially from bottom to top;

[0007] A surrounding layer is arranged on the substrate and the waveguide layer, wherein a groove is arranged in the surrounding layer and is located directly above the waveguide layer;

[0008] A phase change layer and a heating layer are sequentially arranged in the groove from bottom to top, and the phase change layer is directly arranged on the waveguide layer, and the heating layer completely covers the phase change layer;

[0009] An isolation layer is arranged above the surrounding layer, located on both sides of the groove, and in contact with the heating layer;

[0010] A metal layer is arranged on the isolation layer but is not in contact with the heating layer.

[0011] As a preferred embodiment of the present invention, it also includes a covering layer which is arranged above the heating layer and covers the area where the phase change material layer is located.

[0012] As a preferred embodiment of the present invention, the heating layer and the isolation layer are both transparent conductive oxide films.

[0013] As a preferred embodiment of the present invention, the heating layer has a thickness of 150 to 200 nm.

[0014] As a preferred embodiment of the present invention, the thickness of the isolation layer material is 300-1000 nm.

[0015] As a preferred embodiment of the present invention, the material of the heating layer is ITO, In 2 O 3 , one of AZO.

[0016] As a preferred embodiment of the present invention, the isolation layer material is ITO, In 2 O 3 , one of AZO.

[0017] As a preferred embodiment of the present invention, the material of the surrounding layer is a transparent insulating oxide.

[0018] As a preferred embodiment of the present invention, the material of the phase change layer is a compound material composed of at least two elements of Ge, Sb, Te, and Se, or a phase change material formed by doping and modifying the compound material composed of at least two elements of Ge, Sb, Te, and Se with Sn, N, or C elements.

[0019] According to another aspect of the present invention, a method for preparing a phase change optical synapse device array is provided, comprising the following steps:

[0020] S1. Arrange a plurality of phase-change optical synapse units and the same number of directional couplers in an array, and prepare a surrounding layer above the middle section of the arc-shaped waveguide of each phase-change optical synapse unit, wherein the surrounding layer is provided with a groove located directly above the waveguide layer, and the waveguide layer is provided above the substrate;

[0021] S2, embedding a phase change material layer and a heating layer in the groove from bottom to top in sequence;

[0022] S3, preparing an isolation layer located on both sides of the groove and in contact with the heating layer above the surrounding layer;

[0023] S4. The metal electrodes on the isolation layer and not in contact with the heating layer are used to prepare a phase change optical synapse device array.

[0024] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0025] 1. The present invention provides a phase-change optical synapse device array, which is a cross array structure formed by multiple phase-change optical synapse units through the same number of directional couplers, wherein the arc waveguide in each phase-change optical synapse unit contains a phase-change waveguide segment, and a heating layer is arranged above the phase-change material layer, and an isolation layer is arranged between the metal electrode and the waveguide, and the current Joule heat generated by the heating layer under the action of an electric pulse is transferred to the phase-change material layer, causing it to change its state, and at the same time, the metal electrode is shielded from absorbing and interfering with the optical signal in the waveguide by the isolation layer, thereby reducing the optical loss of the array; on this basis, a surrounding layer surrounding the phase-change material is arranged, and the material of the surrounding layer is a transparent insulating oxide, which can well isolate the heating layer from the substrate, reduce the heat dissipation of the substrate, and improve the heating efficiency. Therefore, under the multiple effects of the above-mentioned heating layer, isolation layer and surrounding layer, the heat generated by the heating layer is concentrated in the groove, and the heat loss is reduced to the greatest extent, thereby realizing the accurate regulation of the phase composition of the phase-change material in the groove, further completing the parallel computing processing of the optical signal, and greatly improving the computing density and computing energy efficiency.

[0026] 2. The present invention provides a covering layer above the heating layer that covers the area where the phase change material layer is located. The covering layer reduces the heat loss of the heating layer during the heating process, inhibits the thermal expansion and deformation of the device, and further improves the energy efficiency and durability of the device.

[0027] 3. The material of the surrounding layer of the present invention is a transparent insulating oxide, which can effectively isolate the heating layer from the substrate, reduce the heat dissipation of the substrate, and improve the heating efficiency; the heating layer is a transparent conductive oxide film, which directly heats the phase change material layer, increases the stability of the heating process, and can effectively concentrate the heat on the phase change material.

[0028] 4. The thickness of the heating layer in the heating structure provided by the present invention is preferably 150-200 nm, and the stability is good while ensuring the heating effect.

[0029] 5. The thickness of the isolation layer in the heating structure provided by the present invention is preferably 300-1000 nm, which is thick enough to shield the metal electrode. At the same time, compared with the heating layer, its own resistance is very small and will not cause additional energy dissipation.

[0030] 6. The heating structure provided by the present invention has high uniformity and universality, is applicable to a variety of phase-change optical synapse arrays, is compatible with existing CMOS processes, and has the potential for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The local structure and cross-sectional view of the phase change optical synapse device array provided by the present invention; wherein Figure 1 (a) is a schematic plan view of a local structure, and (b) is a schematic cross-sectional view corresponding to the dotted line portion of the local structure;

[0032] Figure 2 A plan view (left) of a phase-change optical synapse device array provided by the present invention, and a detailed view of a local structure (right);

[0033] Figure 3 Thermodynamic simulation diagram of the heating layer under different heating layer thickness conditions provided by the embodiment of the present invention; wherein, Figure 3 (a) is a thermodynamic simulation diagram of the heating layer when the thickness of the heating layer is 150 nm, (b) is a thermodynamic simulation diagram of the heating layer when the thickness of the heating layer is 175 nm, and (c) is a thermodynamic simulation diagram of the heating layer when the thickness of the heating layer is 200 nm.

[0034] Figure 4 The waveguide propagation mode simulation diagram under different isolation layer thickness conditions provided by the embodiment of the present invention; wherein, Figure 4(a) is a simulation diagram of the waveguide propagation mode under the condition that the isolation layer thickness is 300nm, (b) is a simulation diagram of the waveguide propagation mode under the condition that the isolation layer thickness is 700nm, and (c) is a simulation diagram of the waveguide propagation mode under the condition that the isolation layer thickness is 1000nm;

[0035] Figure 5 A unit resistance distribution diagram of a heating structure portion for a phase change optical synapse device array provided in an embodiment of the present invention, wherein Figure 5 (a) is the current response of the heating structure under different voltages, and (b) is the resistance distribution of the heating structure in the 9 phase-change optical synapse devices in the array, corresponding to 9 phase-change optical synapse devices 6-9, 6-10, 6-11, 7-9, 7-10, 7-11, 8-9, 8-10, and 8-11, respectively. For example, 6-9 is illustrated as the phase-change optical synapse device in the 6th row and 9th column.

[0036] Figure 6 The switching response process of some optical synapse devices used in the phase change optical synapse device array provided in Example 5 of the present invention, wherein Figure 6 (a) to (i) in the figure respectively correspond to the changes in the output power of the 9 phase-change optical synapse devices in Example 5. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] In a first aspect, a phase change optical synapse device array is provided, such as Figure 1 and Figure 2 As shown, the device array is a cross array structure of N rows and M columns formed by N×M phase change optical synapse units through N×M directional couplers; each phase change optical synapse unit includes an arc waveguide and a cross waveguide. Among them, the cross waveguide is composed of a transverse waveguide and a longitudinal waveguide crossing each other. The transverse waveguide is used to continue to input optical signals to the subsequent units, and the longitudinal waveguide is used to add the output optical signals after interacting with the phase change material. Correspondingly, the arc waveguide includes: an input section, a transverse waveguide arranged close to the cross waveguide, which is used to split the input light in the transverse waveguide in proportion; an output section, a longitudinal waveguide arranged close to the cross waveguide, which is used to output the optical signal after the action in the arc waveguide to the longitudinal waveguide of the cross waveguide; and a phase change waveguide section arranged between the input section and the output section, which interacts with the phase change material. The arc waveguide specifically includes:

[0039] A substrate and a waveguide layer are arranged sequentially from bottom to top;

[0040] A surrounding layer is arranged on the substrate and the waveguide layer, wherein a groove is arranged in the surrounding layer and is located directly above the waveguide layer;

[0041] A phase change layer and a heating layer are sequentially arranged in the groove from bottom to top, and the phase change layer is directly arranged on the waveguide layer, and the heating layer completely covers the phase change layer;

[0042] An isolation layer is arranged above the surrounding layer, located on both sides of the groove, and in contact with the heating layer;

[0043] A metal layer is disposed on the isolation layer but is not in contact with the heating layer.

[0044] The material of the surrounding layer is a transparent insulating oxide, specifically SiO 2 or TiO 2 etc.; the heating layer is a transparent conductive film, specifically an ITO film, an AZO film, etc.; the isolation layer is a transparent conductive film, specifically an ITO film, an AZO film, etc.; the heating layer and the isolation layer can be prepared by magnetron sputtering deposition technology and atomic layer deposition technology.

[0045] It should be noted that there are many ways to form the above grooves. It can be obtained by etching away the surrounding layer area directly above the waveguide layer, or it can be obtained by directly growing the surrounding layer around it using the window of the reserved groove by photolithography. There is no limitation here. Ideally, the waveguide layer directly forms the bottom of the groove, and the phase change material layer is in direct contact with the waveguide layer; more preferably, the phase change material layer is in close contact with the waveguide layer; and in general, due to process limitations, there are some intervals between the phase change material layer and the waveguide layer (generally controlled within 100nm and 100nm, preferably controlled within 50nm and 50nm), which also meets the requirements. The thickness of the above surrounding layer is generally set to be greater than or equal to 250nm. Preferably, the thickness of the surrounding layer is 250-500nm.

[0046] It should be noted that the shape of the above-mentioned heat-conducting layer can be a plane trapezoidal structure, a rectangular structure, or a circular structure. Preferably, in an optional embodiment, the shape of the heat-conducting layer is a symmetrical plane rectangular structure. The shape of the heating layer can be a plane trapezoidal structure, a rectangular structure, a circular structure, etc. Preferably, in an optional embodiment, the shape of the heating layer is a symmetrical plane trapezoidal structure, which can effectively concentrate the heat in the middle rectangular area, thereby achieving uniform heating of the phase change material layer.

[0047] By energizing the metal electrode layer, the heating layer generates Joule heat under the action of the current, and the temperature rises. The heat is transferred through contact with the phase change material, causing the temperature of the phase change material to rise. When the temperature threshold is reached, a phase transition occurs, thereby changing the degree of crystallization of the phase change material layer and achieving different states of the phase change material. The phase composition of the phase change material affects the transmittance of the optical synapse.

[0048] For example, Figure 2 As shown, the optical photographs provided for the phase-change optical synapse device array and the heating structure show that the phase-change optical synapse device has a clear outline, the surface of the heating structure is clean and free of impurities, and the heating structure design and device preparation process are excellent. The waveguide layer of the array uses the principle of waveguide directional couplers to complete the distribution and summation of specific optical power in each node. Specifically, the array contains 8×8 directional couplers, matched with 8 input ports and 8 output ports. The 8 directional couplers in each row make the input signal of the current row be evenly divided into 1 / 8 and input into the optical synapse device of the current row, and the 8 directional couplers in each column make the calculation results of the 8 nodes on the column be summed and output.

[0049] In an optional embodiment, a covering layer covering the area where the phase change material layer is located can be provided above the heating layer of the phase change optical synapse device. The material of the covering layer can be SiO 2 、TiO 2 And other materials.

[0050] In an optional embodiment, the metal electrode is a multilayer electrode formed by stacking any multiple metals of gold, titanium, platinum and chromium. The waveguide material can be a silicon waveguide or silicon nitride, and the phase change material can be a compound composed of two or more elements of Ge, Sb, Te, and Se.

[0051] In an optional embodiment, the metal electrode is a multilayer electrode formed by stacking any multiple metals of gold, titanium, platinum and chromium.

[0052] In an optional embodiment, the substrate material and waveguide material of the phase-change optical synapse device are silicon waveguide or silicon nitride.

[0053] In an optional embodiment, the phase change material can be a compound composed of two or more elements among Ge, Sb, Te, and Se, and can also be a new phase change material formed by doping and modifying the above-mentioned phase change material (a compound composed of two or more elements among Ge, Sb, Te, and Se) with elements such as Sn, N, and C.

[0054] In an optional embodiment, the thickness of the heating layer is 150-200 nm.

[0055] Specifically, Figure 3The temperature distribution diagram of the heating layer thermal field under different heating layer thickness conditions (other parameters are the same); (a) is the heating layer temperature distribution under the condition of heating layer thickness of 150nm, (b) is the heating layer temperature distribution under the condition of heating layer thickness of 175nm, and (c) is the heating layer temperature distribution under the condition of heating layer thickness of 200nm. Figure 3 It can be seen from the figure that when the thickness of the heating layer exceeds 150nm, the heat and temperature generated by the heating layer are sufficient to cause the phase change material to undergo a phase transition; at the same time, experimental tests have shown that when the thickness of the heating layer is less than 150nm, the heating layer is prone to fracture and damage, resulting in device failure. Figure 3 It can be seen from (a)(b)(c) that the heat and temperature area generated by the heating layer increase with the thickness of the heating layer. At the same time, when the thickness of the heating layer is 200nm, the heat and temperature area generated have greatly exceeded the phase change material area. If the thickness continues to increase, it will cause unnecessary energy loss. In summary, the optimal thickness of the heating layer is 150~200nm.

[0056] In an optional implementation, the thickness of the isolation layer material is 300-1000 nm.

[0057] Specifically, Figure 4 It is the simulation diagram of waveguide propagation mode under different isolation layer thickness conditions (other parameters are the same); Figure 4 (a) is a simulation diagram of the waveguide propagation mode under the condition that the isolation layer thickness is 300nm, (b) is a simulation diagram of the waveguide propagation mode under the condition that the isolation layer thickness is 700nm, and (c) is a simulation diagram of the waveguide propagation mode under the condition that the isolation layer thickness is 1000nm. Figure 4 It can be seen from the figure that when the thickness of the heating layer exceeds 300nm, the interference of the metal electrode on the propagation of the optical signal in the waveguide is already at a low level; and when the thickness of the isolation layer is further reduced, the light absorption will increase and the signal interference will be enhanced. Figure 4 It can be seen from (a), (b), and (c) that the shielding effect of the isolation layer increases with the thickness of the isolation layer. At the same time, when the thickness of the isolation layer is 1000nm, the propagation loss is negligible. If the thickness continues to increase, it will cause unnecessary material waste. In summary, the optimal thickness of the isolation layer is 300 to 1000nm.

[0058] In a second aspect, a method for preparing a phase change optical synapse device is provided, comprising:

[0059] Preparation of the heating layer: multiple phase change optical synapse units and N×M directional couplers are arranged in an array, and a surrounding layer is prepared above the middle section of the arc waveguide of each phase change optical synapse unit, wherein a groove is provided in the surrounding layer and is located directly above the waveguide layer, and the waveguide layer is provided above the substrate; a phase change material layer and a heating layer are sequentially embedded in the groove from bottom to top;

[0060] Specifically, a transparent conductive film is deposited on the phase change material in the phase change optical synaptic device array to form a heating layer; in an optional implementation, a heating layer pattern is first prepared on the phase change material layer using an ultraviolet photolithography process, and then a 150-200nm thick ITO transparent conductive film is deposited using magnetron sputtering technology to form a heating layer. It should be noted that in addition to magnetron sputtering technology, deposition technologies such as atomic layer deposition technology can also be used to deposit the heating layer, without limitation.

[0061] Preparation of isolation layer: prepare isolation layers on both sides of the heating layer of the phase change optical synapse device array; wherein the heating layer is a transparent conductive film.

[0062] Specifically, the isolation layer is formed by partially overlapping the heating layer while spanning the entire device array waveguide; in an optional implementation, the isolation layer pattern is first prepared on the phase change material layer by ultraviolet lithography, and then the ITO transparent conductive film with a thickness of 300 to 1000 nm is deposited by magnetron sputtering technology. It should be noted that in addition to magnetron sputtering technology, deposition technologies such as atomic layer deposition technology can also be used to deposit the isolation layer, without limitation.

[0063] Preparation of the metal layer: A first metal electrode and a second metal electrode in contact with the isolation layer are prepared above the isolation layer.

[0064] In an optional implementation, an electrode pattern is prepared on the substrate by ultraviolet lithography, and then the electrode material is deposited by magnetron sputtering technology, and the electrode materials are titanium and platinum, with thicknesses of 10nm and 100nm respectively. It should be noted that the magnetron sputtering technology used here is not the only optional technology, and other technologies such as new electron beam evaporation technology (EBE) can also be used for preparation.

[0065] It should be noted that the photolithography process used above is not limited to ultraviolet photolithography, and photolithography processes such as electron beam lithography (EBL) may also be used.

[0066] In order to further illustrate the modulation effect of the phase change optical synapse device array heating structure provided by the present invention, the following is a detailed description in conjunction with a specific embodiment: Specific implementation method one:

[0068] According to the above preparation method, an array as described in the present invention is obtained. In the phase change optical synapse device array heating structure under this embodiment, the heating layer transparent conductive film is a 180nm ITO film deposited by magnetron sputtering, the isolation layer transparent conductive film is a 1000nm ITO film deposited by magnetron sputtering, and the electrode materials are titanium and platinum with a thickness of 10 / 100nm.

[0069] When the heating structure in this embodiment is applied to a phase-change optical synapse device array, better resistance uniformity can be obtained. Figure 5 As shown, 9 phase-change optical synapse devices in the array (for example, 6-9 are phase-change optical synapse devices with 6 rows and 9 columns) are randomly selected for switching response. (a) is the current response of the heating structure under different voltages, and the slope of the curve represents the resistance value of the unit heating structure. (b) is the resistance distribution of the heating structure in the 9 phase-change optical synapse devices in the array. Figure 6 for Figure 5 The changes in the optical output power of the corresponding 9 phase-change optical synapse devices under the action of crystallization pulses and amorphization pulses show that the 9 phase-change optical synapse devices all obtain uniform, stable and reversible switching responses. Specific implementation method 2:

[0071] According to the above preparation method, an array as described in the present invention is obtained. In the phase change optical synapse device array heating structure under this embodiment, the heating layer transparent conductive film is a 180nm AZO film deposited by magnetron sputtering, the isolation layer transparent conductive film is a 1000nm AZO film deposited by magnetron sputtering, and the electrode materials are titanium and platinum with a thickness of 10 / 100nm.

[0072] When the heating structure in this embodiment is applied to a phase change optical synapse device array, the physical property parameters of ITO and AZO are obtained as shown in Table 1. It can be seen that their parameters are similar, so they can achieve similar heating and shielding effects.

[0073] Table 1: Physical properties of ITO and AZO

[0074]

[0075] In summary, the present invention uses a transparent conductive film as a heating material and an insulating material. By controlling the thickness of the heating material and the thickness of the insulating layer, the heating effect of the heater and the signal shielding effect of the insulating layer can be effectively adjusted, thereby achieving effective modulation of the state of the phase change material in the phase change optical synapse device array, thereby achieving the switching response of the array. In addition, the heating structure provided by the present invention is universal, compatible with existing CMOS processes, and has the potential for large-scale application.

[0076] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are all within the protection scope of the present invention.

Claims

1. A phase change optical synapse device array, characterized in that: The device array is a cross array structure formed by a plurality of phase-change optical synapse units through the same number of directional couplers; each of the phase-change optical synapse units includes an arc waveguide and a cross waveguide, and the arc waveguide includes an input section, an output section, and a phase-change waveguide section arranged between the input section and the output section, so that the optical signal of the input section is coupled into the transverse waveguide of the cross waveguide, and the optical signal after the action of the phase-change waveguide section is coupled out from the output section to the longitudinal waveguide of the cross waveguide; wherein the phase-change waveguide section includes: A substrate and a waveguide layer are arranged sequentially from bottom to top; A surrounding layer is arranged on the substrate and the waveguide layer, wherein a groove is arranged in the surrounding layer and is located directly above the waveguide layer; A phase change layer and a heating layer are sequentially arranged in the groove from bottom to top, and the phase change layer is directly arranged on the waveguide layer, and the heating layer completely covers the phase change layer; An isolation layer is arranged above the surrounding layer, located on both sides of the groove, and in contact with the heating layer; A metal layer is arranged on the isolation layer but is not in contact with the heating layer.

2. The phase change optical synapse device array according to claim 1, characterized in that: It also includes a covering layer which is arranged above the heating layer and covers the area where the phase change material layer is located.

3. The phase change optical synapse device array according to claim 1, characterized in that: The heating layer and the isolation layer are both transparent conductive oxide films.

4. The phase change optical synapse device array according to claim 1, characterized in that: The thickness of the heating layer is 150-200 nm.

5. The phase change optical synapse device array according to claim 1, characterized in that: The thickness of the isolation layer material is 300-1000nm.

6. The phase change optical synapse device array according to claim 1, characterized in that: The material of the heating layer is one of ITO, In2O3 and AZO.

7. The phase change optical synapse device array according to claim 1, characterized in that: The isolation layer material is one of ITO, In2O3 and AZO.

8. The phase change optical synapse device array according to claim 1, characterized in that: The material of the surrounding layer is transparent thermal insulation oxide.

9. The phase change optical synapse device array according to claim 1, characterized in that: The material of the phase change layer is a compound material composed of at least two elements of Ge, Sb, Te, and Se, or a phase change material formed by doping and modifying the compound material composed of at least two elements of Ge, Sb, Te, and Se with Sn, N, or C elements.

10. A method for preparing a phase change optical synapse device array, characterized in that: The steps include: S1. Arrange a plurality of phase-change optical synapse units and the same number of directional couplers in an array, and prepare a surrounding layer above the middle section of the arc-shaped waveguide of each phase-change optical synapse unit, wherein the surrounding layer is provided with a groove located directly above the waveguide layer, and the waveguide layer is provided above the substrate; S2, embedding a phase change material layer and a heating layer in the groove from bottom to top in sequence; S3, preparing an isolation layer located on both sides of the groove and in contact with the heating layer above the surrounding layer; S4. The metal electrodes on the isolation layer and not in contact with the heating layer are used to prepare a phase change optical synapse device array.

Images