Multifunctional waveguide optoelectronic device based on phase change material and application thereof

Abstract

The application belongs to the technical field of optoelectronic devices, and relates to a multifunctional waveguide type optoelectronic device based on a phase change material and application thereof, in particular to applying a positive bias voltage pulse to the optoelectronic device to convert the phase change material from a crystal state to an amorphous state, at this time, the optoelectronic device is used as a heater or a waveguide phase shifter; a first positive bias voltage pulse is applied to the optoelectronic device to completely convert the phase change material from the crystal state to the amorphous state, then a second positive bias voltage pulse is applied to the optoelectronic device to convert the phase change material from the amorphous state to the crystal state, at this time, the optoelectronic device is used as an optical attenuator or an optical detector or a waveguide phase shifter, the voltage of the first positive bias voltage pulse is greater than the voltage of the second positive bias voltage pulse, and the pulse time of the first positive bias voltage pulse is less than the pulse time of the second positive bias voltage pulse, so that high-loss and low-loss switching of the optoelectronic device can be realized, and the optoelectronic device has a unique function of integration of detection and adjustment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optoelectronic devices, and particularly relates to a multifunctional waveguide-type optoelectronic device based on a phase change material and an application thereof. BACKGROUND

[0002] With the explosive growth of information in the era of artificial intelligence, the demand for efficiency of computing systems is also growing rapidly. Optical neural networks can achieve efficient computing with more accurate information extraction and fewer network parameters, and are considered as an ideal candidate for future neural morphological hardware processors. The inherent high parallelism and high computing bandwidth of photonic devices bring unique advantages to optical computing. Photodetectors, as the core components of high-speed optical communication and optical computing systems, are developing towards higher responsivity, wider wavelength range, and higher bandwidth. However, as an electro-optical conversion device, almost all light is converted into carriers to form current, which has high loss characteristics and limits the reconstruction ability of a single device.

[0003] Phase change materials are functional materials that undergo a structural transition from amorphous to crystalline state near the phase transition temperature, resulting in a change in electronic structure from insulating to metallic state, thereby causing a significant difference in optical constants before and after the phase transition, and being used to regulate specific optical properties. Phase change materials have the ability to be repeatedly erased and written, and also have non-volatility, which can reconstruct photonic circuits and have great application potential in optical computing.

[0004] Prior art CN 106782645 B discloses an integrated photodetector based on phase change nanowires and a testing method thereof, which aims to realize multi-level storage by applying an electrical pulse or an erasing optical pulse to the electrodes to cause phase change in the nanowires. The light intensity detection is performed by introducing light from a grating and monitoring the transmittance through an external photodetector, so the device itself does not have the function of a photodetector, thus greatly weakening the scalability and reconfigurability of the phase change material device. Prior art CN 110739359 A discloses an α-phase GeTe wide-spectrum infrared detector and a preparation method thereof, which realizes an infrared detector by directly depositing an α-phase GeTe photosensitive layer on a substrate and then depositing a metal electrode layer, for infrared thermal imaging. However, this detector is a surface receiver without a light waveguide layer structure, and cannot form a photonic circuit, which is not conducive to low-cost and large-scale on-chip integration with other optoelectronic devices. Prior art CN 217086596 U discloses a novel photovoltaic device and an ultraviolet photodetector, which uses a thermal phase change material as the phase change material for the design of a heat absorption layer to quickly dissipate light heat energy, without utilizing the optical phase change material and its own photoelectric properties to realize a photodetector. SUMMARY

[0005] In view of the defects of the prior art, the present application provides a multifunctional waveguide type optoelectronic device based on phase change material, which solves the technical problems of single function and non-reconfigurability of the prior art, and achieves the technical effect of the optoelectronic device with multiple functions, reconfigurability and high integration.

[0006] According to a first aspect of the present application, a kind of optoelectronic devices based on phase change material, its structure is specifically as follows: from bottom to top, it includes substrate layer, lower cladding layer, optical waveguide, phase change material layer, phase change material buffer layer, the optical waveguide includes P-type doped waveguide, N-type doped waveguide, undoped waveguide, the P-type doped waveguide, N-type doped waveguide is located at the two ends of the undoped waveguide respectively, the phase change material layer covers the undoped waveguide, the phase change material buffer layer completely covers the phase change material layer, the top of the P-type doped waveguide and N-type doped waveguide is connected with first metal electrode, second metal electrode respectively, the P-type doped waveguide, N-type doped waveguide, undoped waveguide and the surface not covered by phase change material buffer layer are covered by upper cladding layer;The top of the first metal electrode and the second metal electrode exposes the upper cladding layer.

[0007] According to another aspect of the present application, a kind of optoelectronic devices based on phase change material, its structure is specifically as follows: from bottom to top, it includes substrate layer, lower cladding layer, optical waveguide, phase change material buffer layer, the optical waveguide includes P-type doped waveguide, N-type doped waveguide, undoped waveguide, the P-type doped waveguide, N-type doped waveguide is located at the two ends of the undoped waveguide respectively, the top of the undoped waveguide is provided with recess, the recess is filled with phase change material layer, the top of the phase change material layer is covered with phase change material buffer layer;The top of the P-type doped waveguide and N-type doped waveguide is connected with first metal electrode, second metal electrode respectively, the P-type doped waveguide, N-type doped waveguide, undoped waveguide and the surface covered by phase change material buffer layer are covered by upper cladding layer, and the top of the first metal electrode and the second metal electrode exposes the upper cladding layer.

[0008] According to another aspect of the present application, a kind of optoelectronic devices based on phase change material, its structure is specifically as follows: from bottom to top, it includes substrate layer, lower cladding layer, undoped optical waveguide, phase change material layer, phase change material buffer layer, the phase change material layer covers the middle region of the undoped optical waveguide, the four peripheral edges of the undoped optical waveguide are not covered by the phase change material layer, the inside of the phase change material layer is respectively spaced embedded P-type doped waveguide and N-type doped waveguide at two ends, the top of the phase change material layer is connected with first metal electrode and second metal electrode at two ends respectively, the phase change material buffer layer covers the region of the top of the phase change material layer not covered by first metal electrode and second metal electrode, the undoped optical waveguide, phase change material layer, phase change material buffer layer are covered by upper cladding layer, and the top of the first metal electrode and the second metal electrode exposes the upper cladding layer.

[0009] Preferably, the material of the phase change material layer is selected from one or more of Ge x Te 1-x , Sb x Se 1-x , Sb x S 1-x , Sb x Te 1-x , Ge x S 1-x , Ge x Se 1-x , Ge x Sb y Te 1-x-y , Ge x Se y Te 1-x-y , Ge x Sb y S z Se 1-x-y-z , Ge x Sb y Se z Te 1-x-y-z ; when the material of the phase change material layer is Ge x Te 1-x , Sb x Se 1-x , Sb x S 1-x , Sb x Te 1-x , Ge x S 1-x , Ge x Se 1-x , x is selected from 0 to 1; when the material of the phase change material layer is Ge x Sb y Te 1-x-y , Ge x Se y Te 1-x-y , wherein x is selected from 0 to 1, y is selected from 0 to 1, and 1-x-y is selected from 0 to 1; when the material of the phase change material layer is selected from Ge x Sb y S z Se 1-x-y-z , Ge x Sb y Se z Te 1-x-y-z , wherein x is selected from 0 to 1, y is selected from 0 to 1, z is selected from 0 to 1, and 1-x-y-z is selected from 0 to 1; x, y, and z each represent the mole percentage of each element.

[0010] Preferably, the material of the phase change material buffer layer is selected from aluminum oxide or aluminum nitride.

[0011] Preferably, the undoped optical waveguide is a strip waveguide or a ridge waveguide.

[0012] According to another aspect of the present application, there is provided an application of the phase change material-based optoelectronic device, a positive bias voltage pulse is applied to the optoelectronic device to convert the phase change material from a crystalline state to an amorphous state, and the optoelectronic device is used as a heater or a waveguide phase shifter.

[0013] According to another aspect of the present application, there is provided an application of the phase change material-based optoelectronic device, a first positive bias voltage pulse is applied to the optoelectronic device to convert the phase change material from a crystalline state to an amorphous state completely, and then a second positive bias voltage pulse is applied to the optoelectronic device to convert the phase change material from an amorphous state to a crystalline state, and the optoelectronic device is used as an optical attenuator or an optical detector or a waveguide phase shifter, the voltage of the first positive bias voltage pulse is greater than the voltage of the second positive bias voltage pulse, and the pulse time of the first positive bias voltage pulse is less than the pulse time of the second positive bias voltage pulse.

[0014] Preferably, when the optoelectronic device is used as an optical detector, a negative bias voltage is applied to the optical detector.

[0015] Preferably, the amplitude of the negative bias voltage is less than or equal to 50 V.

[0016] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0017] 1. The phase change material-based multifunctional optoelectronic device provided by the present application has multiple functions. A pulse voltage with a large voltage and a short pulse time is applied to the optoelectronic device to convert the phase change material from a crystalline state to an amorphous state completely, at this time, the optical waveguide is in a low-loss state, and the optoelectronic device can be used as a heater or a waveguide phase shifter; then a pulse voltage with a small voltage and a long pulse time is applied to the optoelectronic device to heat the optoelectronic device to a crystallization temperature, so that the phase change material is partially or completely converted from an amorphous state to a crystalline state, and the optical waveguide is in a high-loss state, and the optoelectronic device can be used as an optical attenuator or an optical detector.

[0018] 2. The multifunctional optoelectronic device based on phase change material provided by the application, when the optoelectronic device is used as a light detector, the phase change material absorbs light and generates carriers, a negative bias is applied to the light detector, the carriers quickly separate the photo-generated electrons and holes under the action of the internal field and the applied voltage, the drift time of the carriers is shortened, and thus the photocurrent is extracted from the electrode, the negative bias significantly optimizes the performance of the photodetector by enhancing the separation and collection efficiency of the photo-generated carriers, improving the response speed, and reducing the capacitance.

[0019] 3. The reconfigurable multifunctional optoelectronic device based on phase change material provided by the application, which has a reconfigurable function compared to ordinary detectors, and the ordinary detectors almost completely absorb incident light to generate current, while the optoelectronic device of the application works in a high light loss state when high responsivity light power detection is required, and works in a low light loss state when low responsivity light power detection is required, and the state of the phase change material can be switched to avoid affecting the transmission of light power, the high loss and low loss of the optoelectronic device can be switched, and the integrated electrode structure has the unique function of detection and adjustment.

[0020] 4. The reconfigurable multifunctional optoelectronic device based on phase change material provided by the application, which controls the transmission of light with the on-chip optical waveguide structure, is compatible with the CMOS process, and has the advantage of high integration.

[0021] 5. The reconfigurable multifunctional optoelectronic device based on phase change material provided by the application has a phase change material monitoring function. The detection loss, responsivity, dark current and other characteristics of the optoelectronic device have strong correlation with the crystallization degree of the phase change material and film defects, so the optical and electrical characteristics of the optoelectronic device can be used to assist in identifying the state of the film. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The optoelectronic device based on phase change material provided for the embodiment 1 of the application.

[0023] Figure 2 The temperature distribution diagram of the optoelectronic device based on phase change material provided for the embodiment 1 of the application when the positive bias is 4V.

[0024] Figure 3 The optoelectronic device based on phase change material provided for the embodiment 2 of the application.

[0025] Figure 4 The optoelectronic device based on phase change material provided for the embodiment 3 of the application.

[0026] In the figure: 1. Substrate layer; 2. Lower cladding layer; 3. Optical waveguide; 31. P-type doped waveguide; 32. N-type doped waveguide; 33. Undoped waveguide; 34. Phase change material layer; 35. Phase change material buffer layer; 4. Upper cladding layer; 51. First metal electrode; 52. Second metal electrode. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Example 1

[0029] like Figure 1 As shown, a phase-change optoelectronic device has a substrate 1 of silicon and a cladding 2 of silicon dioxide. An optical waveguide 3 is a silicon layer comprising a P-type doped waveguide 31, an N-type doped waveguide 32, and an undoped waveguide 33. The two sides of the optical waveguide 3 are partially etched to form ridge waveguides, with the two sides being P-type doped waveguide 31 and N-type doped waveguide 32 respectively. The ridge region in the middle is undoped and forms an undoped waveguide 33, thus forming a PIN junction. A phase-change material layer 34, which is germanium-antimony-selenium-tellurium alloy (GSST), is deposited near the ridge region, wherein the atomic ratio of germanium, antimony, selenium, and tellurium is 2:2:4:1. A phase-change material buffer layer 35, made of alumina, is deposited above the phase-change material to protect the phase-change material layer 34 and prevent its oxidation. The upper cladding 4 is made of silicon dioxide. The first metal electrode 51 is in contact with the P-type doped waveguide 31, and the second metal electrode 52 is in contact with the N-type doped waveguide 32. The first metal electrode 51 and the second metal electrode 52 can be led out to the outside for easy connection with the external bias circuit.

[0030] The fabrication method for this phase-change-based optoelectronic device involves first preparing an SOI (silicon-on-insulator) wafer, photolithographically forming a silicon ridge waveguide, and then ion implanting at both ends of the ridge waveguide to form a PIN junction. Next, a silicon dioxide cladding layer 4 is deposited and planarized by polishing. Then, vias are created in the electrode region, and the silicon dioxide cladding layer 4 is selectively etched down to the silicon waveguide. A first metal electrode 51 and a second metal electrode 52 are then deposited to fill the vias, forming good contact between the first metal electrode 51, the second metal electrode 52, and the doped silicon waveguide. At this point, the silicon dioxide cladding layer 4 is selectively etched again down to the vicinity of the ridge waveguide, followed by the deposition of a phase-change material layer 34, and then a phase-change material buffer layer 35, forming a surrounding and covering of the phase-change material.

[0031] When a first positive bias voltage pulse is applied to the optoelectronic device, the pulse voltage is 5V and the pulse time is 200ns, the phase change material is completely converted from a crystalline state to an amorphous state. The heater can be used for the phase change material. In the positive bias state, the voltage applied to the P-type semiconductor is greater than the voltage applied to the N-type semiconductor. The PIN junction current generates Joule heat after passing through. According to simulation, when the P-type and N-type doping concentrations are 1E20 / cm 3 , the width of the undoped region 33 is 700nm, the applied voltage is 4V, the thickness of the phase change material layer 34 is 50nm, and the temperature of the phase change material layer 34 region can reach 700℃, as shown in Figure 2 . The crystallization temperature of the phase change material GSST is 250℃, and the amorphization temperature is 630℃. By applying a positive bias voltage pulse to the metal electrode, the phase change material can be completely converted between the crystalline state and the amorphous state.

[0032] When the optoelectronic device changes the crystallization degree by a positive bias voltage pulse, it can be used as a waveguide phase shifter. When the optical wavelength is 1550nm, the refractive index of the GSST amorphous state is 3.326+0.001i, and the refractive index of the crystalline state is 2.083+0.35i. The phase change material has a large refractive index difference between the crystalline state and the amorphous state. According to the phase shift formula (where λ represents the optical wavelength, Δn represents the refractive index change, and L represents the length of the phase change material), a phase shift much larger than 2π can be introduced by changing the crystallization degree.

[0033] A second positive bias voltage pulse is applied to the optoelectronic device, the pulse voltage is 2V and the pulse time is 0.1ms, the phase change material is converted from an amorphous state to a crystalline state, and the optoelectronic device is used as a light detector or a light attenuator. When the optoelectronic device is used as a light detector, a negative bias voltage is applied to the photodetector, the P electrode of the PIN junction is connected to 0V, and the N electrode voltage is 3V. Due to the negative bias state of the PIN junction, the photo-generated carriers are separated from each other under the action of the built-in electric field and the external bias, and are collected by the electrodes at both ends, forming a photocurrent. The photocurrent is related to the loss of the phase change material. The greater the material loss, the greater the photocurrent generated by the optical power in the waveguide. According to simulation, the loss of the amorphous material of the phase change material GSST is 0.04dB / um, and the loss of the crystalline state is 1.2dB / um. The loss contrast is high, and the photodetector can be used. Therefore, by the second positive bias voltage pulse, the phase change material can be partially or completely converted from an amorphous state to a crystalline state, and by switching the state of the phase change material, the photodetector can be switched between high loss and low loss, and even a transparent detector. Compared with the positive bias state, the transit time of the photo-generated carriers is shorter under the reverse bias voltage, and the depletion region capacitance of the photodiode is smaller, which can bring a larger photoelectric response bandwidth.

[0034] Example 2

[0035] As shown in Figure 3As shown, unlike Example 1, the structure of the photonic device based on phase change material is as follows: from bottom to top, it includes substrate layer 1, lower cladding layer 2, optical waveguide 3, phase change material buffer layer 35, upper cladding layer 4, the optical waveguide 3 includes P-type doped waveguide 31, N-type doped waveguide 32, undoped waveguide 33, the two ends of the optical waveguide 3 are P-type doped waveguide 31 and N-type doped waveguide 32 respectively, and the middle region is undoped waveguide 33, the undoped waveguide 33 is embedded with phase change material layer 34, the top of the phase change material layer 34 is exposed after etching the top of the undoped waveguide 33, and the top of the phase change material layer 34 covers the phase change material buffer layer 35; the P-type doped waveguide 31 and the N-type doped waveguide 32 are respectively connected with the first metal electrode 51 and the second metal electrode 52, and the thickness of the upper cladding layer 4 is less than the thickness of the first metal electrode 51 and the second metal electrode 52.

[0036] The phase change material layer (34) uses germanium antimony tellurium alloy (GST), in which the number ratio of germanium, antimony and tellurium atoms is 2:2:5, and the band gap of GST in amorphous state and crystalline state is 0.8eV and 0.5eV respectively. The narrower band gap will bring stronger absorption of light, so that the light absorption length of the detector is shorter, the detector size can be smaller, and the responsivity is higher.

[0037] The method for manufacturing the photonic device based on phase change is as follows: in order to make the phase change material layer 34 have higher overlap with the optical waveguide 3 and increase the efficiency of light absorption to generate carriers, a groove is etched in the undoped waveguide 33, and the phase change material layer 3-4 is formed by atomic layer deposition in the groove, which can reduce interface defects, improve the performance of the detector, and reduce the dark current of the detector. Then cover the phase change material buffer layer 35 with aluminum oxide.

[0038] Example 3

[0039] As Figure 4As shown, different from the embodiment 1, the structure of the optoelectronic device based on phase change material is as follows: from bottom to top, sequentially comprising a substrate layer 1, a lower cladding layer 2, an undoped optical waveguide 33, a phase change material layer 34, a phase change material buffer layer 35, the lower cladding layer 2 completely covers the bottom layer 1, the undoped optical waveguide 33 completely covers the lower cladding layer 2, the phase change material layer 34 covers the middle region of the undoped optical waveguide 33, the four peripheral edges of the undoped optical waveguide 33 are not covered by the phase change material layer 34, the internal two ends of the phase change material layer 34 are spacedly embedded with a P-type doped waveguide 31 and an N-type doped waveguide 32, the top two ends of the phase change material layer 34 are connected with a first metal electrode 51 and a second metal electrode 52 respectively, the phase change material buffer layer 35 covers the region of the phase change material layer 34 which is not covered by the first metal electrode 51 and the second metal electrode 52, the surfaces of the undoped optical waveguide 33, the phase change material layer 34 and the phase change material buffer layer 35 which are not covered are all coated with an upper cladding layer 4, and the thickness of the upper cladding layer 4 is less than the thickness of the first metal electrode 51 and the second metal electrode 52.

[0040] Different from the embodiment 1, the material of the phase change material layer (34) is SbS or SbSe, antimony sulfide can be used for the detection of visible light, antimony selenide can be used for the detection of near-infrared light, and the optical waveguide 3 is a silicon nitride waveguide. Ion implantation is directly performed on the phase change material region, the first metal electrode 51 and the second metal electrode 52 are in contact with the phase change material layer 34 to form an electrical connection, the phase change material layer 34 and the underlying silicon nitride optical waveguide 3 guide the optical field from the silicon nitride to the phase change material layer 34 through mutual coupling, the phase change material absorbs optical power to generate photo-generated carriers, and the carriers are separated in the phase change material to form a photocurrent.

[0041] It is to be understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A optoelectronic device based on phase change materials, characterized in that, Its specific structure is as follows: from bottom to top, it includes a substrate layer (1), a lower cladding layer (2), an undoped optical waveguide (33), a phase change material layer (34), and a phase change material buffer layer (35). The phase change material layer (34) covers the middle region of the undoped optical waveguide (33), and the four edges of the undoped optical waveguide (33) are not covered by the phase change material layer (34). The two ends of the phase change material layer (34) are respectively embedded with a P-type doped waveguide (31) and an N-type doped waveguide (32). The phase change material layer (35) 4) The top two ends are connected to the first metal electrode (51) and the second metal electrode (52) respectively. The phase change material buffer layer (35) covers the area of ​​the top of the phase change material layer (34) that is not covered by the first metal electrode (51) and the second metal electrode (52). The surfaces of the undoped optical waveguide (33), the phase change material layer (34) and the phase change material buffer layer (35) are all covered by the upper cladding layer (4). The tops of the first metal electrode (51) and the second metal electrode (52) are exposed by the upper cladding layer (4).

2. The optoelectronic device based on phase change material according to claim 1, characterized in that, The material of the phase change material layer (34) is selected from Ge x Te 1-x Sb x Se 1-x Sb x S 1-x Sb x Te 1-x 、Ge x S 1-x 、Ge x Se 1-x 、Ge x Sb y Te 1-x-y 、Ge x Se y Te 1-x-y 、Ge x Sb y S z Se 1-x-y-z 、Ge x Sb y Se z Te 1-x-y-z One or more of the following; when the material of the phase change material layer (34) is Ge x Te 1-x Sb x Se 1-x Sb x S 1-x Sb x Te 1-x 、Ge x S 1-x 、Ge x Se 1-x When x is selected from 0 to 1; when the material of the phase change material layer (34) is Ge x Sb y Te 1-x-y 、Ge x Se y Te 1-x-y When x is selected from 0 to 1, y is selected from 0 to 1, and 1-xy is selected from 0 to 1; when the material of the phase change material layer (34) is selected from Ge x Sb y S z Se 1-x-y-z 、Ge x Sb y Se z Te 1-x-y-z , where x is selected from 0 to 1, y is selected from 0 to 1, z is selected from 0 to 1, and 1-xyz is selected from 0 to 1; x, y, and z all represent the mole percentage of each element.

3. The optoelectronic device based on phase change material according to claim 1, characterized in that, The material of the phase change material buffer layer (35) is selected from alumina or aluminum nitride.

4. The optoelectronic device based on phase change material according to claim 1, characterized in that, The undoped optical waveguide (33) is a strip waveguide or a ridge waveguide.

5. The application of an optoelectronic device based on phase change materials according to any one of claims 1-4, characterized in that, A positive bias pulse is applied to the optoelectronic device to cause the phase change material to change from a crystalline state to an amorphous state. At this time, the optoelectronic device is used as a heater or a waveguide phase shifter.

6. The application of an optoelectronic device based on phase change materials according to any one of claims 1-4, characterized in that, A first positive bias pulse is applied to the optoelectronic device to completely transform the phase change material from a crystalline state to an amorphous state. Then, a second positive bias pulse is applied to the optoelectronic device to transform the phase change material from an amorphous state to a crystalline state. At this time, the optoelectronic device is used as an optical attenuator, a photodetector, or a waveguide phase shifter. The voltage of the first positive bias pulse is greater than the voltage of the second positive bias pulse, and the pulse duration of the first positive bias pulse is less than the pulse duration of the second positive bias pulse.

7. The application of the optoelectronic device based on phase change material according to claim 6, characterized in that, When an optoelectronic device is used as a photodetector, a negative bias voltage is applied to the photodetector.

8. The application of the optoelectronic device based on phase change material according to claim 7, characterized in that, The negative bias voltage amplitude is below 50V.

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