WO2015172434A1

WO2015172434A1 - Pyroelectric single crystal sensitive element, preparation method therefor, and pyroelectric infrared detector including pyroelectric single crystal sensitive element

Info

Publication number: WO2015172434A1
Application number: PCT/CN2014/083193
Authority: WO
Inventors: 罗豪甦; 李龙; 赵祥永; 许晴; 杨林荣; 狄文宁; 焦杰; 王升; 李晓兵; 任博; 林迪; 徐海清; 王西安
Original assignee: 中国科学院上海硅酸盐研究所
Priority date: 2014-05-12
Filing date: 2014-07-29
Publication date: 2015-11-19
Also published as: WO2015172587A1; WO2015172585A1; WO2015172590A1; WO2015172589A1; WO2016015462A1; CN103943771A; WO2015172586A1; WO2015172588A1

Abstract

A pyroelectric single crystal sensitive element (7), a preparation method therefor, and a pyroelectric infrared detector. The pyroelectric single crystal sensitive element (7) comprises: an Mn-doped (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ single crystal sensitive element having a thickness of 5-15 micrometres, i.e. a PYC Mn:PMNT; or an Mn-doped (1-x-y)Pb(In_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ high application temperature single crystal sensitive element having a thickness of 5-30 micrometres, i.e. a PYC Mn:PIMNT. The preparation method comprises a series of processes such as chemical mechanical thinning and polishing, wet etching and high temperature annealing. The pyroelectric single crystal sensitive element (7) undergoes polarisation treatment, and is integrated and assembled with an amplification circuit having a specific electrical parameter to obtain an infrared detector, i.e. a PYD. The present invention has a wide application value in uncooled infrared detection fields such as gas detection and fire alarm monitoring.

Description

Pyroelectric single crystal sensitive element, preparation method thereof, and pyroelectric infrared detector including the same

The invention belongs to the field of infrared technology, and relates to a high-performance pyroelectric single crystal sensitive element, a preparation method thereof, and a high-performance pyroelectric infrared detector including the high-performance pyroelectric single crystal sensitive element. Background technique

In the world today, countries are competing to develop infrared detection and imaging technology, which is used in many fields such as military, aerospace, scientific research, medical, industrial and so on. Infrared detectors are mainly divided into photon type infrared detectors and thermal infrared detectors. At present, the common photon-type infrared detectors mainly use a narrow band gap semiconductor material represented by mercury cadmium telluride and an optoelectronic semiconductor material represented by gallium arsenide. However, semiconductor infrared devices generally require low temperature refrigeration, which is bulky, costly, and consumes a lot of power.

The pyroelectric infrared detector developed by the pyroelectric effect of the material has a flat spectral response in the ultraviolet, visible, and infrared bands, and has no need for refrigeration, low power consumption, low noise bandwidth, compact structure, and convenience. The advantages of carrying and low cost have become one of the most eye-catching focuses in the field of infrared technology. With the development of pyroelectric infrared detectors for low cost, low power consumption and miniaturization, pyroelectric infrared detectors are rapidly expanding from the military market to the civilian market, especially in human detection, fire warning, gas analysis, infrared spectrometers. And the field of infrared thermal imaging has played an important role, while reflecting the huge market potential.

The materials currently used in pyroelectric infrared detectors mainly include lead zirconate titanate (PZT), barium titanate.

(BST) and lead bismuth (PST), etc., the materials used for the pyroelectric unit detector are mainly limited to lithium tantalate (LiTaO ₃ ), triglyceride sulfate (TGS) and the like. However, these traditional materials have shortcomings such as low pyroelectric coefficient, large dielectric loss, and unstable physical properties, which are difficult to meet the application requirements of high-performance pyroelectric infrared detectors and their extended products. For example, the more mature commercial LiTaO ₃ infrared detectors have detection levels of only lx l0 ⁸ cm (Hz) ^{, /2} /W to 4>< 10 ⁸ cm (Hz) ^{1 /2} /W. Therefore, at the same time, overcoming the shortcomings of the above materials, exploring new pyroelectric materials with high detection value has become an urgent need for the development of uncooled infrared devices.

Since 1996, Luo Haosu and others have pioneered the successful growth of large-sized high-quality relaxed ferroelectric single crystals using the improved Bridgman method, such as (lx)P Mg _1/3 Nb _2/3 )O. _₃ -xPbTiO ₃ lead magnesium niobate titanate (PMNT abbreviation or PMN-PT), and successfully realized the production of high quality single crystal PMNT (specifically Li literature 1).

Since 2003, Luo Haosu and others have first discovered the excellent pyroelectric properties of relaxed ferroelectric single crystals (such as PMNT), and carried out a large number of related pyroelectric performance optimization and material process research, for example, when the composition of materials When X is between 0.24 and 0.30 and the crystallographic direction is along the spontaneous polarization direction, a PMNT single crystal material having high pyroelectricity is prepared (Patent Document 2).

In order to further reduce the dielectric loss of the material and improve the detection rate of the device, the researchers have grown Mn-doped PMNT single crystal (abbreviated as Mn:PMNT), in which the composition is Mn-doped PMN-0.26PT single crystal, pyroelectric The coefficient reached 17.2x10 - ⁴ C/m ² K and the dielectric loss was reduced to 0.05%. Although the material has excellent performance, since the processing method of the infrared detecting sensitive element of the material is different from the conventional pyroelectric material, especially when the thinning process is performed to improve the infrared detecting performance, the introduced size effect and surface damage effect cause single crystal reduction. The performance of the thin film is seriously degraded, and the problem has not been solved so far, making the new pyroelectric material difficult to be practically used in infrared devices (Paper Literature 1).

In addition, the PMNT single crystal has a low Curie temperature and has certain application restrictions. In order to improve the application range and temperature stability, the chemical composition is used to prepare a high-Curie temperature ternary system bismuth indium magnesium titanate (lxy). ) Pb(In _1/2 Nb _1/2 )O ₃ -yPb(Mg _1/3 Nb _2/3 )O ₃ — xPbTi0 ₃ (referred to as PIMNT or PIN-PMN-PT ) Single crystal has received the attention of researchers. However, due to the complex composition of the ternary system single crystal, it is difficult to adjust the composition of high pyroelectricity, high Curie temperature and low dielectric constant. Therefore, there is no clear research result and public report on the performance optimization of the crystal ( Papers 2).

In addition, the sensitive components of the conventional pyroelectric infrared detector are generally full electrodes, and the area is fixed. If the electrode area is to be reduced to control the electrical parameters of the sensitive components for other purposes, it is not easy to implement, and therefore adjustment of the electrode structure is also required. Improvements in terms.

To date, there has not been developed in the art a high performance pyroelectric single crystal sensitive element that overcomes the above-mentioned drawbacks of the prior art and a high performance pyroelectric infrared detector comprising the high performance pyroelectric single crystal sensitive element.

Patent literature:

Patent Document 1: Chinese Patent CN 1080777C;

Patent Document 2: Chinese Patent CN 100429334C.

Papers:

Papers 1 : L. H. Liu, X. B. Li, X. Wu, Y. J. Wang, W. N. Di, D. Lin, X.Y. Zhao, H. S. Luo, N. Neumann, Appl. Phys. Lett. 95 (2009) 192903;

Paper 2 : P. Yu, FF Wang, D. Zhou, WW Ge, XY Zhao, H. S . Luo, JL Sun, XJ Meng, JH Chu, Appl. Phys. Lett. 92 (2008) 252907 Summary

The present invention provides a novel pyroelectric single crystal sensitive element, a method of preparing the same, and a pyroelectric infrared detector comprising the same, thereby solving the problems in the prior art.

In one aspect, the invention provides a pyroelectric single crystal sensitive element comprising:

Μn-doped (1-x)Pb(Mg _1/3 Nb _2/3 )O ₃ -xPbTiO ₃ single crystal sensitive element with a thickness of 5-15 μηι, ie PYC Mn: PMNT, where 0.26≤x≤0.29 And the crystallographic direction is [111], or 0.35 ≤ x ≤ 0.40, and the crystallographic direction is [001]; or

Mn doped (lxy)Pb(In _1/2 Nb _1/2 )O ₃ - yPb(Mg _1/3 Nb _2/3 )O ₃ - xPbTiO ₃ single crystal sensitive element with a thickness of 5-30 μηι, ie PYC Mn: PIMNT, where 0.28≤x≤0.30, 0.47≤y≤0.57, 0.15≤lxy≤0.23, and the crystallographic direction is [111], or 0.38≤x≤0.42, 0.30≤y≤0.39, 0.20≤lxy ≤ 0.29, and the crystallographic direction is [001].

In another aspect, the present invention provides a method of preparing the above pyroelectric single crystal sensitive element, the method comprising the steps of:

(i) thinning and polishing the relaxed ferroelectric single crystal, wherein the relaxed ferroelectric single crystal comprises: Mn doped (1-x)Pb(Mg _1/3 Nb _2/3 )O ₃ -xPbTiO ₃ single crystal, where 0.26 ≤ x ≤ 0.29, and the crystallographic direction is [111], or 0.35 ≤ x ≤ 0.40, and the crystallographic direction is [001]; or Mn doped (lxy) Pb (In _{1 / 2} Nb _1/2 )O ₃ - yPb(Mg _1/3 Nb _2/3 )O ₃ - xPbTiO ₃ single crystal, 0.28 ≤ x ≤ 0.30, 0.47 ≤ y ≤ 0.57, 0.15 ≤ lxy ≤ 0.23, and crystallographic direction Is [111], or 0.38 ≤ x ≤ 0.42, 0.30 ≤ y ≤ 0.39, 0.20 ≤ lxy ≤ 0.29, and the crystallographic direction is [001];

(ii) wet etching of the thinned and polished single crystal sensitive element;

(iii) High-temperature annealing of the wet-etched single crystal sensitive element to obtain a Μη:ΡΜΝΤ single crystal sensitive element having a thickness of 5-15 μηι, or a Μη:ΡΙΜΝΤ single crystal sensitive element having a thickness of 5-30 μηι.

In a preferred embodiment, in step (i), chemical mechanical polishing is used for thinning and polishing, wherein the abrasive is made of green silicon carbide powder or alumina powder, and the polishing liquid is made of acid having a particle diameter of not more than 100 nm or Alkaline silica sol.

In another preferred embodiment, in step (ii), the etching solution for wet etching comprises HF, NF and H ₂ O, the etching time is ≤ 2 hours; and, if necessary, before the wet etching, The thinned and polished single crystal sensitive element is diced to reduce the size of the single crystal sensitive element. In another preferred embodiment, in the step (iii), the annealing atmosphere is an oxygen-rich atmosphere, and the annealing temperature is 200-1000. C, annealing time ≥ 5 hours.

In still another aspect, the present invention provides a pyroelectric infrared detector, g卩 PYD, comprising: a base having a lead;

a package with one or more windows enclosing the base to form a receiving space; one or more of the above-mentioned pyroelectric single crystal sensitive elements disposed in the receiving space Sensitive elementary chip;

And a heterogeneous electrode respectively disposed on the upper surface and the lower surface of the pyroelectric single crystal sensitive element, or a distributed electrode disposed on the upper and lower surfaces of the pyroelectric single crystal sensitive element;

Covering an absorbing layer on the upper surface of the pyroelectric single crystal sensitive element;

a support for supporting the pyroelectric single crystal sensitive element;

Amplifying circuit using voltage mode or current mode.

In a preferred embodiment, the isothermal electrodes of the upper and lower surfaces of the pyroelectric single crystal sensitive element have different configurations or different sizes.

In another preferred embodiment, the distributed electrode on the upper and lower surfaces of the pyroelectric single crystal sensitive element comprises: a single electrode on the upper surface and a divided electrode on the lower surface that is not connected.

In another preferred embodiment, the absorbing layer is formulated as a mixture of multi-walled carbon nanotubes, nano-ferric oxide or nano-carbon powder and alcohol, and is covered by intermittent multiple spraying. Surface, the infrared absorption rate of the absorption layer is ≥90%; the stent adopts a fine, low thermal conductivity alumina ceramic support, which is supported at the center of the pyroelectric single crystal sensitive element to realize infrared Detect the thermal dangling of the sensitive component.

In another preferred embodiment, the matching resistance of the voltage mode amplifying circuit! ^ is reduced to much less than 100 GQ, the feedback capacitance C _{f of} the current mode amplifying circuit is ≤ 10 pF, and the feedback resistance R _{f is} reduced to much less than 100 GQ. DRAWINGS

The objects and features of the present invention will become more apparent from the detailed description of the accompanying claims

Figure 1 illustrates the effect of wet etching on the performance of Mn: PMNT single crystal sensitive elements in accordance with embodiments of the present application. 2 illustrates the performance impact of different post-treatment processes on Mn: PMNT single crystal sensitive elements in accordance with embodiments of the present application.

Figure 3 illustrates a multi-walled carbon nanotube absorber layer and its infrared absorption properties in accordance with embodiments of the present application. FIG. 4 shows a schematic structural view of an infrared detector according to an embodiment of the present application.

Figure 5 illustrates the frequency response of the infrared detector response rate and the specific detection rate in voltage mode in accordance with an embodiment of the present application.

Fig. 6 is a graph showing the relationship between the response rate of the infrared detector and the specific detection rate in the current mode according to an embodiment of the present application.

FIG. 7 is a schematic diagram of a structure of a sensitive element distributed electrode according to an embodiment of the present application.

Figure 8 illustrates the frequency response of the specific detection rate of an infrared detector including distributed electrodes in accordance with an embodiment of the present application.

Figure 9 shows the relationship between the dielectric properties of a high Curie temperature Mn: PIMNT (29/31/40) single crystal as a function of temperature and frequency, in accordance with an embodiment of the present application. detailed description

The invention aims to obtain a pyroelectric single crystal sensitive element composed of a relaxed ferroelectric single crystal (Mn: PMNT or Mn: PIMNT) having high pyroelectric properties, a preparation method thereof, and a method for preparing the single crystal sensitive element A pyroelectric infrared detector that is uniquely adapted to its high performance.

In a first aspect of the invention, there is provided a high performance pyroelectric single crystal sensitive element comprising: Mn doped (lx) Pb (Mg _1/3 Nb _2/3 ) O having a thickness of 5-15 μηι ₃ -xPbTiO ₃ single crystal sensitive element; or Mn doped (lxy)Pb(In _1/2 Nb _1/2 )O ₃ - yPb(Mg _1/3 Nb _2/3 )O _{3 with a} thickness of 5-30 μηι - xPbTiO ₃ single crystal sensitive element.

In the present invention, a binary system (PMNT) relaxation ferroelectric single crystal Mn: PMNT single crystal sensitive element having excellent comprehensive performance is selected, and its formulation is 0.26 ≤ x ≤ 0.29, and the crystallographic direction is spontaneous polarization [111] Orientation, pyroelectric coefficient is greater than 11.0x lO— ⁴ C/m ² K, dielectric loss is reduced to 0.05%, Curie temperature is greater than 120 °C; or formula is 0.35≤x≤0.40, and crystallographic direction is [001 ].

In the present invention, a high Curie temperature ternary system (PIMNT) relaxation ferroelectric single crystal Mn: PIMNT single crystal sensitive element is also selected, and the formulation thereof is 0.28 ≤ x ≤ 0.30, 0.47 < y < 0.57, 0.15 < lxy < 0.23 , and the crystallographic direction is [111]; or the formula is 0.38 ≤ x ≤ 0.42, 0.30 ≤ y ≤ 0.39, 0.20 ≤ lxy ≤ 0.29, and the crystallographic direction is spontaneous polarization [001] orientation, and the Curie temperature can be greatly improved. Above 200 °C, the pyroelectric coefficient is greater than 6.0x lO_ ⁴ C/m ² K, dielectric loss is 0.05%, and the dielectric constant is also greatly reduced (compared to the binary system can be reduced by nearly half), thus making up for the reduction of the pyroelectric coefficient, which greatly increases the Based on the operation of the single crystal and the temperature of use, the detection value is comparable to that of the binary system.

In the present invention, a pyroelectric single crystal sensitive element having an extremely thin thickness can also be selected. The above-mentioned different components of the relaxed ferroelectric single crystal can be processed into a very thin thickness pyroelectric single crystal sensitive element, such as Mn: PMNT sensitive element thickness is 5-15 μηι precisely controllable, Μη: thickness of ΡΙΜΝΤ sensitive element It is precisely controllable for 5-30 μηι.

In a second aspect of the invention, a method for preparing a high performance pyroelectric single crystal sensitive element is provided, the method comprising:

Chemical mechanical thinning polishing of ytterbium-doped lanthanum magnesium titanate (; Μ: ΡΜΝΤ) or yttrium indium magnesium titanate (; Μ: ΡΙΜΝΤ) relaxation ferroelectric single crystals for specific components and crystal orientation Method

a wet etching method designed for a relaxed ferroelectric single crystal sensitive element;

A high temperature annealing process that optimizes the pyroelectric properties of the single crystal sensitive element is utilized.

In the present invention, in order to obtain an extremely thin pyroelectric single crystal sensitive element, a chemical polishing process is used to thin and polish a large-sized wafer of the same formulation and crystallographic orientation, and the obtained single crystal sensitive element has a size of ≥ 20 χ 20 mm ² (Or can also be used for other sizes of wafer thinning and polishing, according to specific requirements;), thickness is precisely controllable, error ±1 μηι, where the abrasive can be made of green silicon carbide powder or alumina powder of different particle size, polished The solution may be an acidic or alkaline silica sol having a particle size of not more than 100 nm, such as 50-80 nm, to ensure low surface damage.

In the present invention, the green silicon carbide powder has high hardness and good consistency, can effectively increase the thinning rate, reduce the scratch amount of the single crystal surface, and improve the thinning quality; the silica sol polishing liquid with a smaller particle diameter can reduce the surface roughness of the wafer. Degree and surface damage layer thickness, help to improve the dielectric properties of single crystal sensitive elements.

In the present invention, in order to solve the size effect and surface effect introduced by the thinning, the large single crystal sensitive element or the small single crystal sensitive element obtained by cutting a large single crystal sensitive element, such as a size of 2 mm x 2 mm A small piece of single crystal sensitive element is subjected to wet etching, wherein the etching liquid is preferably a corrosion inhibiting liquid containing HF, NH ₄ F and H ₂ O, and is applicable to corrosion of the relaxed ferroelectric single crystal, and the etching time is preferably ≤ 2 hours. Wet etching can remove the surface damage layer of single crystal sensitive elements introduced by chemical mechanical polishing, and solve the key problem of dielectric performance degradation.

In the present invention, in order to reduce the surface stress and dielectric loss of the single crystal sensitive element, the single crystal sensitive element after the etching is subjected to a high temperature annealing treatment, wherein the annealing atmosphere is an oxygen-rich atmosphere, preferably oxygen, and the annealing temperature is preferably 200-1000. °C, annealing time is preferably ≥ 5 hours. Annealing can remove the defects caused by the single crystal during the thinning process The trapping and surface stress further reduce the dielectric loss and dielectric noise of the single crystal sensitive element, and improve the detection performance of the pyroelectric detector.

In the present invention, the post-treatment annealing process can reduce the internal defects of the relaxed ferroelectric single crystal on the one hand, and remove the surface stress and lattice distortion introduced by the chemical mechanical polishing on the other hand.

In a third aspect of the invention, a high performance pyroelectric infrared detector is provided, comprising: a base provided with a lead;

a package with one or more windows enclosing the base to form a receiving space; one or more of the aforementioned pyroelectric single crystal sensitive elements disposed in the receiving space Sensitive elementary chip;

And a heterogeneous electrode disposed on the upper surface and the lower surface of the single crystal sensitive element, or a distributed electrode disposed on the upper and lower surfaces of the single crystal sensitive element;

An absorbing layer covering the upper surface of the single crystal sensitive element;

a support for supporting the single crystal sensitive element;

Amplifying circuit using voltage mode or current mode.

In the present invention, the unique heterogeneous electrode designed to improve the performance of the sensitive element is: the electrodes of the upper surface and the lower surface have different configurations or different sizes (the electrode size is adjustable), and can induce an asymmetric region in the polarization. The flipping of the domain structure optimizes the pyroelectric performance of the single crystal sensitive element.

In the present invention, the distributed electrodes designed to improve the performance of the detector are: the upper electrode is a single electrode, and the lower electrode is a two-part divided electrode that is not connected, and the distance is adjustable.

In the present invention, the distributed electrode, that is, a single electrode whose upper surface is circular or other shape, and the lower surface is a two-part non-connected divided electrode, the structure of the pyroelectric detector sensitive element does not need to take out the upper surface It can be used to absorb infrared light, increase the absorption efficiency of infrared light, and reduce the capacitance of the sensitive element while the pyroelectric coefficient remains unchanged, which greatly shortens the response time of the detector.

In the present invention, the absorbing layer is formulated by multi-walled carbon nanotubes, nano-ferric oxide or a mixture of nano-carbon powder and alcohol, and is covered on the surface of the upper electrode by intermittent multiple spraying. The absorption layer has an infrared absorption rate of ≥90%.

In the present invention, the stent adopts an alumina ceramic support having a very fine and low thermal conductivity, such as 0.6 mm x 0.6 mm x 1.0 mm, which is supported at the center of the pyroelectric single crystal sensitive element. , realizes the thermal suspension of the infrared detecting sensitive element.

In the present invention, the circuit mode of the smaller matching resistor is employed by utilizing the characteristics of the pyroelectric single crystal sensitive element. In the present invention, a pyroelectric detector prepared by relaxing a ferroelectric single crystal sensitive element can achieve optimal performance with a smaller matching resistance, such as 20 ΟΩ, which is 100% than that used in a conventional infrared detector. The price of ΟΩ is greatly reduced, which can greatly reduce the preparation cost of the detector to a certain extent, and can reduce the cost by 10% in certain cases.

In the present invention, the matching resistance of the voltage mode amplifying circuit! ^ The optimal infrared detection performance can be achieved at a distance of less than 100. The preferred matching resistance value is 20 GQ, which effectively reduces the manufacturing cost of the detector.

In the present invention, the feedback capacitance C _f ≤ 10 pF and the feedback resistance of the current mode amplifying circuit are far less than 100 to obtain an optimal infrared detecting performance, and the preferred feedback resistance R _f is 20 Ο Ω, which effectively reduces the detector. Preparation costs.

In the present invention, only one of the pyroelectric single crystal sensitive elements may be included, or a plurality of the pyroelectric single crystal sensitive elements may be included, and different pyroelectric single crystal sensitive elements may be compensated in series or in parallel. It can also be used as an infrared detection sensitive component alone.

In the present invention, the pyroelectric single crystal sensitive element can be used to prepare a high-performance pyroelectric infrared detector of various structures, which has the characteristics of ultra-high ratio detection rate, low noise, high sensitivity and the like.

In the present invention, the pyroelectric single crystal sensitive element has a high pyroelectric coefficient, a low dielectric loss, a suitable dielectric constant, and an absorption layer such as a multi-walled carbon nanotube having a high infrared absorption rate. Pyroelectric infrared detector with high response rate, low noise and high detection rate.

In the present invention, the use of a relaxed ferroelectric single crystal sensitive element as a sensitive element material for preparing a pyroelectric infrared detector can greatly improve the detection level of the detector in the field of pyroelectric infrared. The absorbing layer may be a multi-walled carbon nanotube (short), and its absorption rate is ≥90%, which can effectively improve the response rate of the detector. The main advantages of the invention are:

The pyroelectric single crystal sensitive element of the invention has high pyroelectric performance and high detection excellent value, high pyroelectric coefficient, small dielectric loss and stable physical property, and can satisfy high performance pyroelectric infrared detector and its extension The application requirements of the product; the obtained pyroelectric infrared detector has the advantages of high detection rate, low noise and high response rate, and has wide application value in the field of uncooled infrared detection such as gas detection and fire alarm monitoring. Example

The invention is further illustrated by the following specific examples. However, it should be understood that these embodiments are only used The invention is not to be construed as limiting the scope of the invention. Test methods not specified for the specific conditions in the following examples are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. All percentages and parts are by weight unless otherwise indicated. The dielectric properties of the materials involved in the examples were measured using an Agilent Model 4294A Impedance Analyzer (Agilent Technologies, Inc.) and approximated from a plate capacitor; the pyroelectric coefficient after single crystal polarization is autonomous. The dynamic method pyroelectric coefficient measurement system is established. After the single crystal is heated and polarized along the spontaneous polarization direction, the AC drive temperature range is 1 °C and the frequency is 45 mHz. The single crystal sensitive element chip is passed through The single crystal sensitive element is obtained by polarization treatment; the electrode is deposited by magnetron sputtering; the response rate of the pyroelectric detector is measured by an independently established black body infrared response test system, and the device noise is passed through Agilent 35670 A. The dynamic signal analyzer (Agilent Technologies, Inc.) measured the detection rate based on the theoretical formula of the blackbody detection rate, calculated from the measured response rate and noise. Example 1

A lmol% Mn doped Mn: PMNT (71/29) single crystal sensitive element with a crystallographic orientation <111>, a size of 20x20 mm ² and a thickness of 15 ± 1 μηι. The properties of the sputtered heterogeneous electrode after polarization are as follows: Curie temperature is 135 °C, tripartite-tetragonal phase transition temperature is 108 °C, dielectric constant ≤ 750, pyroelectric coefficient; ?≥12.0 X 10" ⁴ C/m ² K. Example 2

A 0.5 mol% Mn doped Mn: PIMNT (29/31/40) high application temperature single crystal sensitive element, crystallographic orientation <001>, size 20x20 mm ² , thickness 20±1 μηι. The performance of the polarized electrode after polarization is as follows: Curie temperature is 216 °C, compared with Mn: PMNT single crystal sensitive element use temperature (low temperature phase transition temperature) increased by nearly 110 °C, dielectric constant ≤ 450, compared with Mn : PMNT single crystal sensitive element reduced by nearly half, pyroelectric coefficient; ? ≥ 6.0 X l (T ⁴ C / m ² K. Example 3

A method for preparing a pyroelectric single crystal sensitive element, wherein the relaxation ferroelectric single crystal is thinned and polished by a chemical mechanical thinning polishing technique, and the chemical polishing liquid is acidic (pH=3-4) silica sol, silica sol The particle size is generally 50-80 nm. Preparation of large size (20x20 mm ² ) Mn: PMNT (71/29) single crystal sensitive element, single crystal The thickness of the sensitive element can be controlled from 5 μηι to 15 μηι, and then cut into small pieces by a dicing machine as needed to prepare a pyroelectric detector sensitive element chip. Due to the action of chemical mechanical polishing, surface stress and damage layer are introduced. When the thickness of the single crystal sensitive element is reduced to the micron level, the surface effect is more prominent, and the overall dielectric loss of the single crystal chip is significantly increased. The detection performance of the single crystal detector, therefore, through the post-treatment process technology adopted by the present invention, while obtaining extremely thin single crystal sensitive elements, it also minimizes surface damage and defects on the single crystal sensitive element pyroelectric, dielectric The effect of performance enables the preparation of high performance, high quality single crystal sensitive elements.

First, a HF:NF:H ₂ O corrosion inhibitor with a ratio of 8.3:33:58.7 was used to wet-etch the surface of the prepared Mn:PMNT single crystal sensitive element. Figure 1 (a) shows the variation of the thickness of Mn: PMNT single crystal sensitive element with corrosion time. It can be concluded that the corrosion rate of the etching solution to Mn: PMNT single crystal is about 20.8 nm/min. Figure 1 (b) shows the pyroelectric and dielectric properties of Mn: PMNT single crystal sensitive elements as a function of corrosion time. It can be seen that the pyroelectric coefficient increases with the increase of corrosion time, then gradually increases. Smooth; dielectric loss increases with corrosion time, first decreases and then increases. This shows that wet etching can optimize the pyroelectric coefficient of the material to some extent, and the corrosion time is controlled to 15-20 minutes to effectively reduce the dielectric loss of the material.

Thereafter, the etched single crystal sensitive element is annealed to further remove residual mechanical stress on the surface and internal defects of the single crystal. The annealing temperature was 500 °C, the annealing atmosphere was oxygen (oxygen-rich atmosphere), and the annealing time was 10 hours. Figure 2 shows the comparison of the dielectric properties of Mn: PMNT single crystal sensitive elements under different treatment processes. It can be seen from the figure that the single crystal sensitive element is thinned and polished to the micron scale, compared to the bulk material. The electrical loss is significantly increased, but the dielectric loss of the single crystal sensitive element is effectively improved by wet etching and oxygen annealing. Example 4

A 1% Mn-doped Mn:PMNT (71/29) single crystal sensitive element was placed in an electrode mask, and a Ni-Cr electrode and a Ni-Cr/Au electrode were sputter deposited on the upper and lower surfaces by magnetron sputtering. The electrode is polarized by means of temperature-increasing polarization. The polarization conditions are: temperature is 120±2 °C, polarization electric field is 2±0.2 kV/mm, and polarization time is 15±l min. A multi-walled carbon nanotube and alcohol are used to form a uniform solution by ultrasonic vibration, and an infrared absorbing layer is prepared on the surface of the single crystal sensitive element chip by spraying, as shown in FIG. 3( a ). Fig. 3(b) shows the infrared absorption performance of the multi-walled carbon nanotube absorber layer in the wavelength range of 2.5-25 μη, and it can be seen that the infrared absorption rate reaches 99%. Single-layer sensitive element chips of different thicknesses are supported at a single point, respectively The voltage mode and current mode integrated circuit are packaged in a metal tube casing to obtain a high detection rate pyroelectric infrared unit detector. As shown in FIG. 4, FIG. 4 shows a schematic structural view of the prepared pyroelectric detector. , including: board 1, electrode leads 2a, 2b, alumina adiabatic support 3, conductive electrode 4, gold electrode (bottom) 5, Ni-Cr electrode (bottom) 6, pyroelectric single crystal sensitive element 7, Ni -Cr electrode (top) 8, infrared absorbing layer 9 and gold wire lead 10. The performance test circuit was independently established to characterize the detector. The infrared response test system was established by using the black body radiation source system and the dynamic signal analyzer. The temperature of the black body was precisely controlled by the temperature controller, and it was selected as 500 K. The infrared radiation passed through the machine. The modulating disk is modulated into a square wave output of different frequencies. The detector is placed 10 cm away from the light exit hole of the black body radiation source, and the exit aperture is Φ 10 mm.

Figure 5 shows the frequency response of the 15 μηι single crystal sensitive element detector in the prepared voltage mode with a specific detection rate in the range of 0.5 Hz-100 Hz. The voltage response rate at 10 Hz is 27,710 mV, and the specific detection rate is 1.17x10 ⁹ cm'(Hz) ^1/2 /W. Figure 6 (a) - (c) shows the relationship between the response rate and the specific detection rate of the 15 μηι single crystal sensitive element detector in the prepared current mode. It can be seen from the above observation that the above etching and oxygen annealing treatment After that, the dielectric loss of the single crystal sensitive element can be reduced from 2% to 0.5%, which greatly improves the detection level of the detector, which can be increased from 1.2χ10 ⁹ cm-(Hz) ^1/2 /W to 2.17><10 ⁹ cnr(;H _Z y ^/2 /W. In addition, as the thickness of the single crystal sensitive element decreases, the detector voltage response rate and the specific detection rate increase significantly. When 8 μηι, the voltage response rate is 2.0xl0 ⁵ V/W, up to 2 times the 20 μηι single crystal sensitive element detector; ΙΟ μηι, the specific detection rate is 2.63χ 10 ⁹ cm Hz) ^1/2 /W, obviously better than 20 μηι single crystal sensitive element detector (2.04xl0 ⁹ _C m Hz) ^1/2 /W), which is 5 times that of the current commercial LiTaO ₃ infrared detector. Example 5

The treated 1% Μn-doped Mn:PMNT (71/29) single crystal sensitive element was placed in an electrode mask, and the distributed electrode was magnetron sputtered, and the Ni-Cr/Au electrode was sputter deposited on the lower surface. The electrode area is 0.5x2 mm ² , the spacing is 0.1 mm, 0.5 mm, 1 mm and 1.5 mm; the upper surface Ni-Cr electrode is a Φ 2.5 mm round electrode.

The electrodes at both ends of the sensitive element are polarized at 2kV/mm and -2 kV/mm, respectively, forming reverse polarization, as shown in the figure.

7 shows, including: infrared absorption black layer 11, Ni-Cr electrode 12, pyroelectric material 13, Ni-Cr/Au electrode

14, P represents the polarization orientation. The two sensitive electrodes of the sensitive element are led out by the gold wire, and the voltage mode amplifying circuit composed of the FET and the 20 G resistor is packaged in the TO39 pipe seat (Shanghai Kefa Precision Alloy Material Sales Co., Ltd.). A multi-walled carbon nanotube and an alcohol mixture are sprayed on the surface of the above sensitive element chip to prepare an absorption layer, thereby obtaining a high-frequency pyroelectric infrared detector. Adopting an independently established electrical modulation infrared response test system The detector is characterized by performance. Figure 8 shows the frequency response of the 20 μηι high-frequency pyroelectric infrared detector with a detection rate based on the electrode structure. The specific detection rate at the electrode spacing of 0.5 mm and 10 Hz is 1.39. χ 10 ⁹ _C n H _Z ) ^1/2 /W. The detection performance is better than the 20 μηι Mn: ΡΜΝΤ single crystal sensitive element detector in the above voltage mode, and maintains a high specific detection rate at a high frequency (100 Hz), and is significantly better than the current commercial LiTaO ₃ Infrared detectors meet the needs of higher frequency applications.

The upper surface of the sensitive element of the pyroelectric detector of the structure does not need to take out the electrode, and all of them can be used for absorbing infrared light, thereby increasing the absorption efficiency of the infrared light; in addition, the structure is greatly maintained under the condition that the pyroelectric coefficient remains substantially unchanged. The capacitance of the sensitive element is reduced, that is, the equivalent dielectric constant of the sensitive element is lowered, so that the dielectric noise is one order of magnitude smaller than the resistance noise, and the advantage of relaxing the high pyroelectric coefficient of the ferroelectric single crystal is simultaneously reduced. The disadvantage of its high dielectric constant is reduced, and the specific detection rate of the detector is improved to some extent, and the higher specific detection rate is maintained at a higher frequency. This structure provides a new pyroelectric detector structure that is easy to miniaturize and integrate, meeting the requirements of modern detectors for low cost, low power consumption, and compatibility with integrated circuits. Example 6

Using a high Curie temperature of 0.5% Mn: PIMNT ( 29/31/40 ) single crystal, along the [001] crystal orientation, the wafer is diced by size 4x4x0.5 mm ³ , sputtered and polarized for performance Test, polarization conditions: The temperature is 150±2 °C, the polarization electric field is 4±0.2 kV/mm, and the polarization time is 15±1 min. Figure 9 shows the dielectric properties of a single crystal as a function of temperature and frequency. It can be seen from Fig. 9(a) that the Curie temperature of the single crystal of this component reaches 216. C, more binary Mn: PMNT (21/79) single crystal, the upper limit of the operating temperature is increased by nearly 110 °C, which significantly improves the temperature stability of the device during use. It can be seen from Fig. 9(b) that the dielectric constant of the single crystal of this component is nearly half lower than that of the binary Mn: PMNT (21/79) single crystal, and 350 at 1 kHz, which compensates for the high PT content. The pyroelectric coefficient of the single crystal is lowered, so that the detection value of the single crystal can be compared with the binary Mn: PMNT (21/79) single crystal.

The chemical mechanical thinning polishing technique is used for thinning and polishing. The chemical polishing liquid is alkaline (pH=9-10) silica sol, and the particle size of the silica sol is generally 50-80 nm. The tetragonal phase Mn: PIMNT single crystal sensitive element was prepared, and the thickness of the single crystal sensitive element was controlled at 20 μηι, and then the extremely thin single crystal sensitive element was cut into 2.5 Χ 2.5 mm ² using a dicing machine to prepare pyroelectric Infrared detector sensitive element chip. The surface of the prepared high Curie temperature tetragonal phase Mn: PIMNT single crystal sensitive element was also wet-etched using a HF:NH ₄ F:H ₂ O corrosion inhibitor with a ratio of 8.3:33:58.7. After the end of the corrosion, the oxygen is enriched in the single crystal sensitive element sensitive element. Atmosphere) Annealing, annealing temperature of 600 °C, annealing time of 20 hours to remove surface damage layers, residual mechanical stress and internal defects of the single crystal.

Magnetron sputtering is used to deposit, for example, a Ni-Cr electrode and a Ni-Cr/Au electrode on the upper and lower surfaces of the Mn:PIMNT ( 29/3 1/40 ) single crystal sensitive element as the upper electrode and the lower electrode, this embodiment For example, the electrode size of the upper electrode Φ 2.5 ηπη and the lower electrode Φ 2.0 mm was used. The sensitive element is also polarized by means of temperature-increasing polarization. The polarization conditions are: temperature is 150±2 °C, polarization electric field is 4±0.2 kV/mm, and polarization time is 15±1 min. The multi-walled carbon nanotubes and the alcohol mixture are sprayed on the surface of the single crystal sensitive element chip to prepare an absorption layer. The single-crystal sensitive element chip and the electronic component are packaged in a metal tube shell by using a voltage mode and a current mode integrated circuit form, thereby obtaining a high Curie temperature pyroelectric infrared unit detector, and FIG. 7 shows a self-designed voltage mode. And current mode integrated circuit board schematic. The performance of the detector was also characterized by an independently established infrared response test system. The voltage response rate and specific detection rate of the 20 μηι high Curie temperature single crystal sensitive element detector at 10 Hz in the prepared voltage mode reached 30020 V/W, 1. 15 χ 10 ⁹ cm-(Hz) ^{1/2, respectively.} /W, the voltage response rate and specific detection rate of the 20 μηι high Curie temperature single crystal sensitive element detector at 10 Hz in the prepared current mode reached 78500 V/W, 1.74 χ 10 ⁹ cm-(Hz) ^{1/ respectively. 2} / W, and significantly better than the current commercial LiTaO ₃ infrared detector, achieving a combination of high application temperature and high performance. All documents mentioned in the present application are hereby incorporated by reference in their entirety in their entireties in the the the the the the the the the In addition, it is to be understood that various modifications and changes may be made by those skilled in the art in the form of the appended claims.

Claims

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A pyroelectric single crystal sensitive element comprising:

2. A method of preparing a pyroelectric single crystal sensitive element according to claim 1, the method comprising the steps of:

(i) thinning and polishing the relaxed ferroelectric single crystal, wherein the relaxed ferroelectric single crystal comprises: Mn doped (1-x)Pb(Mg _1/3 Nb _2/3 )O ₃ -xPbTiO ₃ single crystal, where 0.26 ≤ x ≤ 0.29, and the crystallographic direction is [111], or 0.35 ≤ x ≤ 0.40, and the crystallographic direction is [001]; or Mn doped (lxy) Pb (In _{1 / 2} Nb _1/2 )O ₃ - yPb(Mg _1/3 Nb _2/3 )O ₃ - xPbTiO ₃ single crystal, wherein 0.28<x<0.30, 0.47<y<0.57, 0.15≤lxy≤0.23, and The crystallographic direction is [111], or 0.38 ≤ x ≤ 0.42, 0.30 ≤ y ≤ 0.39, 0.20 ≤ lxy ≤ 0.29, and the crystallographic direction is [001];

(ii) wet etching of the thinned and polished single crystal sensitive element;

(iii) High temperature annealing of the wet-etched single crystal sensitive element to obtain a Mn: PMNT single crystal sensitive element having a thickness of 5-15 μηι, or a Mn: PIMNT single crystal sensitive element having a thickness of 5-30 μη.

3. The method according to claim 2, wherein in step (i), chemical mechanical polishing is used for thinning and polishing, wherein the abrasive is made of green silicon carbide powder or alumina powder, and the polishing liquid is made of a particle size. Acidic or alkaline silica sol not exceeding 100 nm.

4. The method according to claim 2, wherein in the step (ii), the etching solution subjected to wet etching comprises HF, NH ₄ F and H ₂ O, and the etching time is ≤ 2 hours; It is desirable to cut the thinned and polished single crystal sensitive element to reduce the size of the single crystal sensitive element before performing wet etching.

The method according to claim 2, wherein in the step (iii), the annealing atmosphere is an oxygen-rich atmosphere, the annealing temperature is 200-1000 ° C, and the annealing time is ≥ 5 hours.

6. A pyroelectric infrared detector, PYD, which includes:

a base with a pin; a package with one or more windows enclosing the base to form a receiving space; one or more pyroelectric single crystals of claim 1 disposed in the receiving space by polarization treatment Sensitive elementary chip composed of sensitive elements;

a support for supporting the pyroelectric single crystal sensitive element;

Amplifying circuit using voltage mode or current mode.

The pyroelectric infrared detector according to claim 6, wherein the hetero-electrodes of the upper surface and the lower surface of the pyroelectric single crystal sensitive element have different configurations or different sizes.

8. The pyroelectric infrared detector according to claim 6, wherein the distributed electrode on the upper and lower surfaces of the pyroelectric single crystal sensitive element comprises: a single electrode on the upper surface and a disconnected portion on the lower surface electrode.

The pyroelectric infrared detector according to any one of claims 6 to 8, wherein the absorption layer is formulated by multi-walled carbon nanotubes, nano-ferric oxide or nano-carbon powder, and alcohol. a mixture, and covering the upper surface in a batch multiple spraying manner, the absorption layer has an infrared absorption rate of ≥90% _; the stent adopts a fine, low thermal conductivity alumina ceramic support, which is The central position of the pyroelectric single crystal sensitive element is supported to realize the thermal suspension of the infrared detecting sensitive element.

The pyroelectric infrared detector according to any one of claims 6 to 8, wherein a matching resistance Re of the voltage mode amplifying circuit is reduced to be much smaller than 100 GQ, and the current mode amplifying circuit The feedback capacitor C _f ≤ 10 pF, and the feedback resistor R _f drops far less than 100 GQ.