High-uniformity room temperature medium wave infrared array detector for passive imaging detection and application thereofTechnical Field
The invention belongs to the technical field of medium-wave infrared signal detection, and particularly relates to a high-uniformity room-temperature medium-wave infrared column detector for passive imaging detection and application thereof.
Background
The room temperature infrared detector can perform passive imaging detection under the uncooled condition. The detector does not depend on a refrigerating system, and has the advantages of low power consumption, miniaturization and integration. The passive imaging detection capability can enable the detector to directly detect infrared radiation signals from the target object without depending on an external illumination light source, and the device has the advantages of all-weather operation and strong concealment. In order to improve the passive imaging efficiency of the detector, an effective method increases the number of pixels of the detector. For a single-pixel device, in order to image a target object, the single-pixel device needs to be scanned in a two-dimensional plane in sequence, so that the time consumption is long, and the imaging speed is low. Further, the number of pixels is increased in one dimension to form a line detector. During imaging, only one-dimensional scanning is needed to be carried out on the line detector in the direction perpendicular to the line, so that the imaging time can be shortened, and the rapid imaging of a target can be realized. Therefore, the room temperature mid-wave infrared array detector with passive imaging detection capability is of great significance.
The van der Waals layered material has no dangling bond on the surface, and has the characteristics of thin atomic thickness, high mobility and strong light absorption. The detector prepared based on the Van der Waals material has the performances of low dark current, quick response, low noise and high sensitivity, and has obvious advantages in the field of room temperature infrared photoelectric detection. The current methods for manufacturing the infrared multi-pixel detector include wet transfer, thermal evaporation, magnetron sputtering and the like.
The method for transferring transition metal chalcogenide by a large-area wet method can realize the preparation of wafer-level multi-pixel devices. On one hand, the photosensitive material adopted in the preparation of the device is usually a few-layer two-dimensional material, so that the light absorption efficiency is low, and on the other hand, the photosensitive material is a wide-band gap material, and the detection band can only cover short-wave infrared rays or even near infrared rays and is not suitable for medium-wave infrared detection. The material prepared by adopting the thermal evaporation and magnetron sputtering methods is polycrystalline, has defects and poor uniformity, and causes mobility reduction and carrier capture probability increase, which are manifested by slow response speed, low detection rate and low uniformity.
Therefore, how to solve the problems of poor consistency and poor interface contact quality of each pixel in a multi-pixel array in a room temperature infrared detector and the problem of irregular arrangement of each pixel synchronously, and provide a high-uniformity room temperature infrared array detector for passive imaging detection and application thereof are technical problems to be solved urgently by those skilled in the art.
Disclosure of Invention
A first object of the present invention is to provide a high uniformity room temperature mid-wave infrared column detector for passive imaging detection, which addresses the problems of the prior art.
For this purpose, the above object of the present invention is achieved by the following technical solutions:
The high-uniformity room temperature medium wave infrared array detector for passive imaging detection is characterized by comprising a silicon substrate, a photosensitive area and chromium/gold metal electrodes arranged at two ends of the photosensitive area, wherein the photosensitive area is a molybdenum disulfide/black phosphorus heterojunction area formed on the silicon substrate, the molybdenum disulfide/black phosphorus heterojunction is integrated on a substrate in a side-by-side and interval arrangement mode to form a 1X 8 linear array, the chromium/gold metal electrode at one end is only in contact with the molybdenum disulfide, and the chromium/gold metal electrode at the other end is only in contact with the black phosphorus, and the detector is prepared by the following steps:
S1, mechanically stripping a first single-crystal two-dimensional material MoS2,
S2, transferring a first single-crystal two-dimensional material MoS2 to PDMS;
S3, transferring the first monocrystalline two-dimensional material MoS2 stuck by the PDMS thin sheet to a first silicon wafer to obtain a first monocrystalline two-dimensional material MoS2 positioned on the first silicon wafer;
S4, etching the first monocrystal two-dimensional material MoS2;
S5, transferring the etched first monocrystalline two-dimensional material MoS2 to a second silicon wafer;
s6, copying the step S1 to the step S2, and preparing a PDMS sheet pasted with a single crystal two-dimensional material BP with a narrow band gap;
S7, obliquely placing the PDMS thin sheet, reducing the PDMS thin sheet until one side of the single crystal two-dimensional material BP with the narrow band gap is stopped before contacting with the first single crystal two-dimensional material MoS2 in the step S5, heating the second silicon wafer, and heating the obliquely placed PDMS thin sheet to expand to drive the single crystal two-dimensional material BP with the narrow band gap to gradually cover and contact the single crystal two-dimensional material from one side to the other side, so as to maintain the temperature of the second silicon wafer constant until the first single crystal two-dimensional material MoS2 is completely attached to the single crystal two-dimensional material BP with the narrow band gap, thereby forming a large-size uniform heterojunction which is free of bubbles and residues and complete in material;
s8, cooling the second silicon wafer to room temperature, and then shrinking the PDMS sheet, and lifting the PDMS sheet to obtain a molybdenum disulfide/black phosphorus heterojunction positioned on the second silicon wafer;
S9, preparing chromium/gold metal electrodes at two ends of the molybdenum disulfide/black phosphorus heterojunction;
S10, the molybdenum disulfide/black phosphorus heterojunction is divided into a plurality of pixel units which are from the same single crystal and have uniform heterogeneous interfaces through an etching process, and a 1X 8 line structure with consistent photoelectric response and high detection rate is formed.
The invention can also adopt or combine the following technical proposal when adopting the technical proposal:
In the step S4, the etched first monocrystalline two-dimensional material MoS2 is square.
In the step S5, the etched first monocrystalline two-dimensional material MoS2 is picked up by using a PPC film and transferred to a second silicon wafer to obtain a two-dimensional material MoS2 sample on the second silicon wafer.
In the step S7, the included angle between the PDMS thin sheet and the MoS2 is 5 degrees, and the second silicon wafer is heated to 50 ℃ slowly, and then the temperature is kept constant until the heterojunction is formed.
The preferred technical scheme of the invention is that step S9 specifically comprises spin-coating PMMA on the second silicon wafer in step S8, exposing an electrode window on a molybdenum disulfide/black phosphorus heterojunction by utilizing electron beam lithography, preparing a chromium/gold metal electrode by thermal evaporation, and soaking in acetone to remove the PMMA.
The preferred technical scheme of the invention is that step S10 specifically comprises spin coating PMMA on the second silicon wafer, exposing an etching window by utilizing electron beam lithography, removing a heterojunction exposure area by reactive ion etching, and soaking in acetone to remove PMMA to form the room-temperature wave infrared van der Waals heterojunction line array detector.
As the preferable technical scheme of the invention, the detector is characterized in that an isolation layer is covered on a 1X 8 linear array to protect a molybdenum disulfide/black phosphorus heterojunction region.
A second object of the present invention is to provide the application of a high-uniformity room temperature mid-wave infrared column detector for passive imaging detection, which addresses the problems of the prior art.
For this purpose, the above object of the present invention is achieved by the following technical solutions:
the application of the high-uniformity room temperature medium wave infrared array detector for passive imaging detection is characterized in that the detector is applied to imaging detection.
Compared with the prior art, the invention has the following beneficial effects:
According to the high-uniformity room-temperature medium-wave infrared array detector and the application thereof, the room-temperature medium-wave infrared van der Waals heterojunction array detector is prepared by adopting a temperature auxiliary method, in the preparation process, the temperature of a silicon wafer is adjusted, the inclination angle of PDMS is adjusted, the temperature of the inclined PDMS is regulated and controlled, the small-angle inclination of a PDMS sheet and the expansion and contraction characteristics of the PDMS are utilized to realize the accurate transfer and contact of two-dimensional materials, the preparation of the narrow-band-gap two-dimensional material heterojunction with large-size high-quality and uniform heterogeneous interfaces is realized, the problems of poor consistency of each pixel, poor interface contact quality and irregular pixel arrangement in a multi-pixel array are synchronously solved, so that the room-temperature medium-wave infrared van der Waals heterojunction array detector with high sensitivity and high uniformity can be prepared, the response rate of the detector is improved, the stability and the reliability of the detector are improved, the working temperature of the detector is improved, the medium-wave of the detector is realized under various environmental conditions, the application range of the detector is enlarged, the imaging quality of the detector is improved, and the overall performance of the detector is improved.
In the preparation of the high-uniformity room temperature medium-wave infrared array detector for passive imaging detection, the temperature-assisted PDMS thin sheet is used for preparing a large-area van der Waals layered structure, the advantages of avoiding pollution, precisely controlling a contact area, compatibility and the like are achieved, PDMS contacts with a silicon wafer at a small angle, a two-dimensional material is slowly attached to the silicon wafer through temperature rising expansion of the PDMS, the problems of material wrinkles, bubbles and the like caused by manual or mechanical driving of PDMS to be pressed down are avoided, the contact area is slowly expanded from one side to the other side along a specific direction by utilizing the characteristic of thermal expansion of the obliquely placed PDMS thin sheet until the two-dimensional material is completely covered, the gradual covering mode is beneficial to reducing the generation of bubbles and wrinkles, the quality and uniformity of the van der Waals vertical structure can be improved while the heterojunction of the large-area narrow-band gap material is prepared, and the contact between the van der Waals vertical structures is uniform and defect-free is ensured.
The preparation method of the line array of the high-uniformity room temperature medium-wave infrared array detector for passive imaging detection provided by the invention utilizes a temperature auxiliary method to prepare a narrow-band-gap two-dimensional material heterojunction with large size, high quality and uniform heterogeneous interface so as to ensure the consistency of each pixel in a multi-pixel array and the performance of an integral device, promote the effective transmission of carriers and improve the photoelectric response performance of the device, realize the high-uniformity room temperature medium-wave infrared array detector, and has wide application prospects in the fields of micro-fluidic chip manufacture, flexible electronic devices, medical appliances, electronic appliances, environmental monitoring, tissue engineering and the like.
Drawings
FIG. 1 is a flow chart of a method for preparing a high-uniformity room temperature medium wave infrared array detector for passive imaging detection of the invention;
FIG. 2 is a schematic diagram of a method for preparing a high-uniformity room temperature medium wave infrared array detector for passive imaging detection according to the present invention;
FIG. 3 is a schematic diagram of a structure of a high-uniformity room temperature mid-wave infrared array detector for passive imaging detection according to the present invention;
FIG. 4 is a schematic diagram of the structure of a molybdenum disulfide/black phosphorus heterojunction region of the present invention;
FIG. 5 is a schematic diagram of an imaging detection application of a high uniformity room temperature mid-wave infrared column detector of the present invention for passive imaging detection;
FIG. 6 is a graph of response time of a high uniformity room temperature mid-wave infrared column detector for passive imaging detection of the present invention;
FIG. 7 is a graph of the detection rate of a high-uniformity room temperature mid-wave infrared array detector for passive imaging detection in accordance with the present invention;
FIG. 8 is a comparison of the imaging map obtained in FIG. 5 with a prior art unit imaging map;
in the drawing, a chromium/gold metal electrode 1, a first monocrystal two-dimensional material MoS2 2, a narrow-band-gap monocrystal two-dimensional material BP3, a silicon substrate 4 and a high-uniformity room-temperature medium-wave infrared array detector 100 for passive imaging detection.
Detailed Description
The invention will be described in further detail with reference to the drawings and specific embodiments.
The invention relates to a high-uniformity room temperature medium wave infrared array detector for passive imaging detection, which comprises a silicon substrate, a photosensitive area and chromium/gold metal electrodes arranged at two ends of the photosensitive area, wherein the photosensitive area is a molybdenum disulfide/black phosphorus heterojunction area formed on the silicon substrate, the molybdenum disulfide/black phosphorus heterojunction is integrated on a substrate in a side-by-side and interval arrangement mode to form a 1X 8 linear array, wherein the chromium/gold metal electrode at one end is only in contact with the molybdenum disulfide, and the chromium/gold metal electrode at the other end is only in contact with the black phosphorus, and the detector is prepared by the following steps:
s1, mechanically stripping a first single-crystal two-dimensional material;
S2, transferring the first single-crystal two-dimensional material to PDMS to obtain a first single-crystal two-dimensional material adhered by a PDMS sheet;
S3, transferring the first monocrystalline two-dimensional material stuck by the PDMS thin sheet to a first silicon wafer to obtain a first monocrystalline two-dimensional material positioned on the first silicon wafer;
s4, etching the first single-crystal two-dimensional material;
s5, transferring the etched first monocrystalline two-dimensional material to a second silicon wafer;
S6, repeating the step S1-the step S2, and preparing a PDMS sheet adhered with the single crystal two-dimensional material with a narrow band gap;
And S7, adjusting the angle of the PDMS thin sheet until the included angle between the single crystal two-dimensional material with the narrow band gap and the first single crystal two-dimensional material in the step S5 is 5 degrees, reducing the PDMS thin sheet until the single crystal two-dimensional material with the narrow band gap and the first single crystal two-dimensional material in the step S5 are stopped before being contacted, heating the second silicon sheet, and enabling the single crystal two-dimensional material with the narrow band gap to be slowly covered and contacted with the single crystal two-dimensional material from one side to the other side along a specific direction by thermal expansion of the PDMS thin sheet, so that the temperature of the second silicon sheet is kept constant to maintain the contact state between the PDMS thin sheet and the two-dimensional material until the heterojunction between the first single crystal two-dimensional material and the single crystal two-dimensional material with the narrow band gap is formed, wherein the specific direction refers to the small-angle inclination direction along the PDMS thin sheet.
And S8, slowly cooling the second silicon wafer to room temperature, shrinking the PDMS sheet, and lifting the PDMS sheet to obtain the heterojunction of the large-size first monocrystalline two-dimensional material and the monocrystalline two-dimensional material with the narrow band gap on the second silicon wafer.
And S9, spin-coating PMMA on the silicon wafer in the step S8, exposing an electrode window on the heterojunction by utilizing electron beam lithography, preparing an electrode by thermal evaporation, and soaking in acetone to remove the PMMA.
S10, spin-coating PMMA on the silicon wafer in the step S9, exposing an etching window by utilizing electron beam lithography, removing a MoS2/BP heterojunction exposure area by utilizing reactive ion etching, and soaking in acetone to remove PMMA, thereby forming the room-temperature wave infrared van der Waals MoS2/BP heterojunction line array detector.
The high-uniformity room temperature medium wave infrared array detector for passive imaging detection has the beneficial effects that the problems that a large-size narrow-band-gap single crystal two-dimensional material cannot be realized, a large-size single crystal cannot be prepared by BP, and a linear array or array device is difficult to form in the prior art are solved by the preparation method, PDMS is contacted with a silicon wafer at a small angle, and the two-dimensional material is slowly attached to the silicon wafer from one side to the other side along a specific direction by temperature rising expansion of the PDMS, so that the problems of material wrinkling, air bubbles and the like caused by manual or mechanical driving of the PDMS are avoided. The method can prepare the room temperature infrared van der Waals heterojunction line detector with high sensitivity and high uniformity.
In the invention, PDMS has good chemical stability and biocompatibility, can be compatible with various two-dimensional materials, and provides possibility for preparing multifunctional van der Waals heterostructures by combining different materials including MoS2/BP heterojunction. By adopting PDMS assisted dry transfer, the expansion and contraction of the PDMS sheet are precisely controlled by slowly increasing and decreasing the temperature of the PDMS material through good stability of the PDMS material, so that precise control and transfer of the two-dimensional material are realized. In addition, by adjusting the PDMS tilt angle, the contact area is slowly widened from side to side in a specific direction during the expansion process, so that the generation of two-dimensional materials and the presence of bubbles at the heterojunction surface can be avoided.
Example 1
As shown in fig. 1 to 4, the high-uniformity room temperature infrared array detector for passive imaging detection of the present invention comprises a silicon substrate 4, a photosensitive region and chromium/gold metal electrodes 1 disposed at two ends of the photosensitive region, wherein the photosensitive region is a molybdenum disulfide/black phosphorus heterojunction region formed on the silicon substrate, the molybdenum disulfide/black phosphorus heterojunction is integrated on a substrate in a side-by-side and spaced arrangement manner to form a1×8 linear array, wherein one end of the chromium/gold metal electrode is only in contact with molybdenum disulfide 2, and the other end of the chromium/gold metal electrode is only in contact with black phosphorus 3, and the high-uniformity room temperature infrared array detector for passive imaging detection of the present invention is prepared by the following steps:
the step S1 specifically comprises the following steps:
S1.1, cutting PDMS with a scalpel to obtain a 20mm x 8mm x 160 μm PDMS sheet, placing the PDMS sheet in the middle of a clean glass slide, wherein one end of the PDMS is fixed by a blue tape. Wherein PDMS is polydimethylsiloxane, which is a synthetic silicone rubber commonly used in laboratory and industrial applications
S1.2, a certain number of monocrystal slices of MoS2 two-dimensional material are placed on a blue adhesive tape, the blue adhesive tape is folded and pasted, and the folding and pasting are repeated for 5-10 times, so that a certain area is covered on the blue adhesive tape by the first monocrystal two-dimensional material MoS2.
The step S2 specifically includes the following steps:
S2.1, sticking the blue adhesive tape stuck with the first monocrystal two-dimensional material MoS2 on the PDMS sheet in the step S1, lightly pressing the PDMS sheet for 1 minute by using a thumb, and then rapidly tearing off the blue adhesive tape stuck with the two-dimensional material from one end fixed with the blue adhesive tape.
S2.2, directly observing the two-dimensional material sample on the PDMS sheet under a microscope, selecting the two-dimensional material sample with a regular shape and a proper thickness, and then cutting and removing redundant PDMS nearby the sample by a surgical knife.
And S3, adhering the residual PDMS sheet adhered with the first single-crystal two-dimensional material MoS2 sample to a clean first silicon wafer to obtain the first single-crystal two-dimensional material MoS2 with a larger size on the first silicon wafer.
In step S4, PMMA is spin-coated on the first silicon wafer, a window of a part to be etched is exposed by utilizing electron beam lithography, and an exposure area is removed by reactive ion etching, so that a rectangular first single-crystal two-dimensional material MoS2 sample is left. Among them, PMMA, which is called polymethyl methacrylate, is a polymer with wide application.
In step S5, the etched rectangular two-dimensional material sample is picked up by the PPC film and transferred to a new second silicon wafer, and the rectangular two-dimensional material sample on the second silicon wafer is obtained. Wherein PPC is polypropylene carbonate, which is a polymer material.
In step S6, the steps S1-S2 are replicated, and the two-dimensional material used in the process is changed to a single crystal two-dimensional material BP with a certain narrow band gap. Wherein BP refers to black phosphorus and is a two-dimensional semiconductor material.
In step S7, the remaining PDMS sheet to which the narrow bandgap two-dimensional material sample is attached is gradually brought close to the second silicon wafer in the preparation step S5 at a tilt angle of 5 °, while aligning the narrow bandgap single crystal two-dimensional material BP with the rectangular two-dimensional material sample in the step S5.
The tilted PDMS sheet was slowly mechanically lowered slowly and stopped before the contact area covered the aligned two-dimensional material sample.
The second wafer temperature was slowly raised to 50 ℃ and then the temperature was kept constant. As the temperature increases, the contact area expands slowly from side to side in one direction as the PDMS sheet expands due to heating, until the contact area completely covers the narrow bandgap single crystal two-dimensional material BP. After the desired temperature is reached, the temperature needs to be kept constant to maintain the contact state between the PDMS sheet and the two-dimensional material until the heterojunction is formed.
The wafer temperature was slowly raised to 50 ℃ during which the PDMS wafer would expand due to heat. Since the thermal expansion coefficient of PDMS is typically 150-200 ppm/K, this means that the length or volume of PDMS will increase by 0.15% to 0.2% at every 1℃increase in temperature. As the temperature increases, the swelling of the PDMS flakes causes the contact area to slowly expand until the single crystal two-dimensional material BP of narrow band gap is completely covered. This step is critical to ensure the quality of the heterojunction, as it needs to ensure that the contact between MoS2 and BP is uniform and defect free.
While current bottom-up growth methods can achieve large-area two-dimensional flake growth, seamless merging of these flakes to form large-area continuous films with well-controlled layer thickness and lattice orientation remains a challenge. In the application, the temperature-assisted PDMS sheet is used for solving the problems, and high-quality and uniform interface can be realized while the large-area narrow-bandgap material heterojunction is prepared.
In the step S8, the temperature is slowly reduced to room temperature, and the PDMS sheet is slowly lifted, so that a large-size and uniform two-dimensional material heterojunction sample sheet positioned on the silicon wafer is obtained.
In steps S9, S10, PMMA is spin coated on the second silicon wafer and an electrode window is exposed on the heterojunction by electron beam lithography, an electrode is prepared by thermal evaporation, and PMMA is removed by immersion in acetone. Spin-coating PMMA on the second silicon wafer, exposing an etching window by utilizing electron beam lithography, removing a heterojunction exposure area by utilizing reactive ion etching, and soaking in acetone to remove PMMA, thereby forming the room-temperature infrared van der Waals heterojunction line array detector.
As shown in fig. 6 and 7, the high-uniformity room temperature medium wave infrared line detector for passive imaging detection has the response speed of 44 mu s, the detection speed of 4X 109 cm Hz1/2W-1, and the high uniformity is maintained basically in response time and detection rate.
As shown in fig. 5 and 8, by performing push broom imaging in the direction perpendicular to the line array at room temperature by using the high-uniformity room temperature mid-wave infrared line detector for passive imaging detection of the present invention, an image of a target area can be directly obtained, and a larger target image can be obtained by performing multi-line push broom detection. The target image obtained by detecting the linear array device is compared with the target image obtained by detecting the single pixel device, so that the root mean square deviation is 14.27, and the device is further proved to have high uniformity.
The above detailed description is intended to illustrate the present invention by way of example only and not to limit the invention to the particular embodiments disclosed, but to limit the invention to the precise embodiments disclosed, and any modifications, equivalents, improvements, etc. that fall within the spirit and scope of the invention as defined by the appended claims.