Miniature long-wave infrared chopper and preparation method thereof

Abstract

The invention relates to a miniature long-wave infrared chopper and a preparation method thereof, and belongs to the field of choppers. The chopper comprises a long-wave infrared window, an upper high-transmittance long-wave infrared transparent electrode, a lower high-transmittance long-wave infrared transparent electrode, an upper long-wave high-transmittance insulating layer, a lower long-wave high-transmittance insulating layer, a phase-change film layer, an upper transparent electrode leading-out structure and a lower transparent electrode leading-out structure. An alternating electric field is applied through the electrodes, the phase change film layer is induced to generate reversible phase change, and the long wave transmittance before and after phase change is greatly different, so that the wave band is modulated. Compared with a traditional mechanical chopper, the miniature chopper of the multilayer film structure has the advantages of being small in size, low in power consumption, high in stability and the like, can be directly integrated in a packaging structure of a pyroelectric infrared focal plane detector chip, and greatly reduces the size of a system.

Description

Technical Field

[0001] This invention relates to the field of choppers, and in particular to a miniature long-wave infrared chopper and its fabrication method. Background Technology

[0002] Compared with thermistor-type focal plane detectors, pyroelectric infrared focal plane detectors have many advantages such as wide response spectrum, low low-frequency noise, easy detection of dynamic targets, strong environmental adaptability, and protection against sunscald, and have a wide range of applications.

[0003] Due to its working principle, it usually requires an external mechanical chopper for modulation, resulting in an excessively large system size, high power consumption, and poor stability.

[0004] Therefore, it is particularly important to improve the chopper to reduce the size of the detection system, lower the overall power consumption, and improve stability. Summary of the Invention

[0005] The purpose of this invention is to provide a miniature long-wave infrared chopper. This sensor features small size, low power consumption, high stability, and can be directly integrated into the detector chip package structure without external components. This invention employs a thin-film optical switching chopper, utilizing the electric field-induced phase transition thin film to generate a reversible phase transition. The significant difference in long-wave infrared transmittance before and after the phase transition produces a "chopping" effect. This miniature chopper can be directly integrated into the pyroelectric detector chip package structure, greatly reducing the size of the detection system, lowering overall power consumption, and improving stability.

[0006] According to a first aspect, the present invention provides a miniature long-wave infrared chopper, the chopper comprising:

[0007] Long-wave infrared window,

[0008] The following structures are deposited sequentially from bottom to top on a long-wave infrared window: a lower transparent electrode, a lower insulating layer, a phase change thin film layer, an upper insulating layer, an upper transparent electrode, and upper and lower transparent electrode lead-out structures.

[0009] The long-wave infrared window is made of infrared silicon or germanium coated with an anti-reflection film;

[0010] Both the upper and lower transparent electrodes are made of materials with high transmittance and low resistivity in the long-wave infrared band.

[0011] Both the upper and lower insulating layers are thin films with high transmittance and high resistivity in the long-wave infrared band.

[0012] The phase change thin film layer is a VO2 thin film that can achieve a reversible phase change under the induction of an electric field, and the transmittance in the long-wave infrared band shows a large difference before and after the phase change.

[0013] Furthermore, the upper and lower transparent electrodes are made of Bi2Se. 2.4 .

[0014] Furthermore, both the upper and lower insulating layers are ZnSe or ZnS thin films.

[0015] Furthermore, the thickness of the lower transparent electrode is 5-10 nm; the thickness of the lower insulating layer is 100-200 nm.

[0016] Furthermore, the phase change layer has a thickness of 100 nm.

[0017] Furthermore, the thickness of the upper insulating layer is 100-200 nm.

[0018] Furthermore, the thickness of the upper transparent electrode is 5-10 nm.

[0019] This invention also provides a method for fabricating a miniature long-wave infrared chopper, the method comprising the following steps:

[0020] (1) A transparent electrode is deposited on a long-wave infrared window using a magnetron sputtering process, with a portion reserved for electrode lead-out.

[0021] (2) A lower insulating layer is prepared on the lower transparent electrode using a magnetron sputtering process;

[0022] (3) A phase change thin film layer was prepared on the lower insulating layer by ion beam deposition (IBD) and annealed in an inert gas atmosphere;

[0023] (4) An insulating layer is prepared on the phase change thin film layer using a magnetron sputtering process;

[0024] (5) An upper transparent electrode is prepared on the upper insulating layer using a magnetron sputtering process;

[0025] (6) Lead out the upper transparent electrode and the lower transparent electrode.

[0026] The beneficial effects of this invention are:

[0027] Compared to traditional mechanical choppers, the advantages of this invention are that it adopts a microstructure in the form of an optical switch, which is simpler to manufacture and can be directly integrated into the detector chip package structure without external components. This reduces the size, power consumption, and overall stability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the cross-sectional structure of the miniature long-wave infrared chopper in this invention;

[0029] Figure 2 This is a top view schematic diagram of the miniature long-wave infrared chopper in this invention;

[0030] Figure 3 This is a schematic diagram of the fabrication process of the miniature long-wave infrared chopper in this invention.

[0031] Figure 4 This is a graph showing the change in transmittance of the miniature long-wave infrared chopper before and after the phase transition in this invention. Detailed Implementation

[0032] To make the objectives, methods, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings.

[0033] like Figure 1 The diagram shown is a cross-sectional structural schematic of the miniature long-wave infrared chopper of the present invention. The present invention provides a miniature long-wave infrared chopper, the structure of which includes a long-wave infrared window 1, a lower transparent electrode 2, an upper transparent electrode 6, a lower insulating layer 3, an upper transparent electrode 5, a phase change film 4, an upper transparent electrode lead-out structure 7, and a lower transparent electrode lead-out structure 8.

[0034] like Figure 1 As shown, the chopper includes a phase change film 4, which undergoes a periodic reversible phase transition under an alternating electric field. The long-wave infrared transmittance before and after the phase transition shows a significant difference, achieving the "chopping" effect. The upper transparent electrode 6 and lower transparent electrode 2 have a transmittance of over 90% in the long-wave band, ensuring that the transmittance difference before and after the phase transition does not result in significant loss. They are also used to apply the alternating electric field to induce the phase transition. The upper insulating layer 5 and lower insulating layer 3 are located between the electrodes and the phase change film layer, ensuring that the electric field can be applied to the phase change film layer and avoiding Joule heating. The upper and lower transparent electrode lead-out structures 7 and 8 are used to connect to an external power supply.

[0035] like Figure 2 As shown, it is a top view of the chopper structure in this invention, and the functions of each structure are the same as those of the chopper in this invention. Figure 1 The corresponding structures are the same.

[0036] like Figure 3 The diagram shown illustrates the fabrication process of the miniature long-wave infrared chopper in this invention. The fabrication process is as follows:

[0037] (1) Infrared window cleaning: the infrared window is made of germanium or infrared silicon coated with an anti-reflection film. After cleaning, it is used to prepare subsequent film structures.

[0038] (2) Preparation of the lower transparent electrode 2: The lower transparent electrode is deposited on the long-wave infrared window by magnetron sputtering. The thickness of the lower transparent electrode is 5-10 nm and the electrode composition is Bi2Se2.4.

[0039] (3) Preparation of the lower insulating layer 3: The lower insulating layer is deposited on the lower transparent electrode by magnetron sputtering process. The left and right edges of the lower transparent electrode are shielded to leave the electrode lead-out part. The thickness of the insulating layer is 100-200nm and the composition is ZnS or ZnSe.

[0040] (4) Preparation of phase change film 4: A phase change film layer is prepared on the lower insulating layer by ion beam deposition (IBD) process and annealed in an inert gas atmosphere. The film thickness is 100 nm, the phase change temperature is 400-600 °C, and the main component is VO2.

[0041] (5) Preparation of upper insulating layer 5: The upper insulating layer is prepared on the phase change thin film layer by magnetron sputtering. The thickness of the insulating layer is 100-200nm and the composition is ZnS or ZnSe.

[0042] (6) Preparation of the upper transparent electrode 6: The upper transparent electrode is prepared on the upper insulating layer by magnetron sputtering. The thickness of the upper transparent electrode is 5-10 nm and the electrode composition is Bi2Se2.4.

[0043] 7) Fabrication of upper and lower transparent electrode lead-out structures 7 and 8. The lead-out structures are made of Au or Ag.

[0044] Through the above preparation process, the miniature long-wave infrared chopper of this invention can be obtained. The fabrication process of this miniature chopper is simple; a reversible phase transition in the VO2 thin film can be induced by an electric field. Before and after the phase transition, the difference in long-wavelength transmittance reaches more than 50%. Figure 4 As shown, this is the transmission spectrum measured before and after applying voltage to the upper and lower electrode lead-out structures of the miniature chopper. This device type can be directly integrated into the package structure of a pyroelectric detector chip, greatly reducing the size of the detection system itself, lowering overall power consumption, and improving stability.

[0045] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention's technical solutions. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention's technical solutions, still fall within the protection scope of the present invention's technical solutions.

Claims

1. A miniature long-wave infrared chopper, the chopper comprising: Long-wave infrared window (1) A lower transparent electrode (2), a lower insulating layer (3), a phase change thin film layer (4), an upper insulating layer (5) and an upper transparent electrode (6) are deposited sequentially from bottom to top on a long-wave infrared window (1). The long-wave infrared window (1) is an infrared silicon or germanium coated with an anti-reflection film; The upper transparent electrode (6) and the lower transparent electrode (2) are both made of materials with high transmittance and low resistivity in the long-wave infrared band. The upper insulating layer (5) and the lower insulating layer (3) are both thin films with high transmittance and high resistivity in the long-wave infrared band; The phase change thin film layer (4) is a VO2 thin film that can achieve reversible phase change under electric field induction, and the long-wave infrared transmittance shows a large difference before and after the phase change.

2. The miniature long-wave infrared chopper according to claim 1, characterized in that, The upper transparent electrode (6) and the lower transparent electrode (2) are made of Bi2Se. 2.4 .

3. The miniature long-wave infrared chopper according to claim 1, characterized in that, The upper insulating layer (5) and the lower insulating layer (3) are both ZnSe or ZnS thin films.

4. The miniature long-wave infrared chopper according to claim 1, characterized in that, The thickness of the lower transparent electrode (2) is 5-10 nm; the thickness of the lower insulating layer is 100-200 nm.

5. The miniature long-wave infrared chopper according to claim 1, characterized in that, The phase change layer has a thickness of 100 nm.

6. The miniature long-wave infrared chopper according to claim 1, characterized in that, The thickness of the upper insulating layer is 100-200 nm.

7. The miniature long-wave infrared chopper according to claim 1, characterized in that, The thickness of the upper transparent electrode is 5-10 nm.

8. The miniature long-wave infrared chopper according to any one of claims 1-7, characterized in that, It also includes an upper transparent electrode lead-out structure (7) and a lower transparent electrode lead-out structure (8) for connecting the upper transparent electrode (6) and the lower transparent electrode (2) to an external power source, respectively; the upper transparent electrode lead-out structure (7) and the lower transparent electrode lead-out structure (8) are both made of Au or Ag.

9. A method for fabricating a miniature long-wave infrared chopper according to any one of claims 1-8, characterized in that, Includes the following steps: (1) A transparent electrode is deposited on a long-wave infrared window using a magnetron sputtering process, with a portion reserved for electrode lead-out. (2) A lower insulating layer is prepared on the lower transparent electrode using a magnetron sputtering process; (3) A phase change thin film layer was prepared on the lower insulating layer by ion beam deposition (IBD) and annealed in an inert gas atmosphere; (4) An insulating layer is prepared on the phase change thin film layer using a magnetron sputtering process; (5) An upper transparent electrode is prepared on the upper insulating layer using a magnetron sputtering process; (6) Lead out the upper transparent electrode and the lower transparent electrode.

10. The preparation method according to claim 9, characterized in that: In step (3), the annealing temperature is 400-600℃.

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