Method for obtaining size-tunable puf based on phase separation of hybrid halide pure inorganic perovskite

Abstract

The application discloses a method for obtaining size-adjustable PUF based on mixed halogen pure inorganic perovskite phase separation, and the method realizes mixed halogen pure inorganic perovskite microspheres with random distribution of spatial positions and halogen proportions by introducing ion exchange through a two-step chemical vapor deposition method. According to laser beam array scanning, the application encodes collected fluorescent responses into keys, and based on the phenomenon of laser irradiation-induced mixed halogen pure inorganic perovskite phase separation, the application obtains independent keys under different laser intensities. By randomly combining the above independent keys, the application expands the key size and coding space, and can realize size-adjustable PUF with higher security.

Description

Technical Field

[0001] This invention relates to the fields of information security and semiconductor optoelectronics technology, specifically to a method for obtaining a size-tunable physically unclonable function (PUF) based on the phase separation of mixed halogen pure inorganic perovskites. Background Technology

[0002] Counterfeiting has always been a pressing issue for society, permeating various manufacturing sectors from consumer goods to professional technologies. To address these problems, products are typically labeled with specific tags such as barcodes and watermarks. Currently, the digital keys used in electronic systems are usually stored in non-volatile memory (NVM). These digital keys exist based on mathematical methods rather than physical entities, making them easily copied and tampered with. Therefore, tamper-proof keyless arrays (PUFs) that are unclonable and unpredictable offer a novel solution.

[0003] In the development of particle arrays (PUFs), electrical PUFs are vulnerable to being deciphered by machine learning due to the linear response of Ohm's law. They can be forged and tampered with through brute force and are susceptible to external factors such as temperature and electromagnetic environment, all of which greatly limit their practical applications. Optical PUFs, on the other hand, are based on the interaction between randomly distributed micro / nano media and excitation light, making them far more secure than electrical PUFs. However, the micro / nano structures currently used in optical PUFs are almost all obtained through methods such as inkjet printing, blade coating, surface-enhanced Raman scattering (SERS) of metals, and laser engraving, which have drawbacks such as cumbersome processes, poor uniformity, fixed dimensions, and complex certification processes.

[0004] The invention titled "A Method for Preparing Cryptographic Primitives Based on Pure Inorganic Perovskite Crystals and Its Application" (Patent No. 202110489949.2) discloses a method for preparing cryptographic primitives based on pure inorganic perovskite crystals and its application. This includes preparing a pattern of compositionally segregated pure inorganic perovskite crystals and encoding rules for cryptographic primitives; controlling the solubility by adjusting the temperature during evaporation and crystallization to obtain pure inorganic perovskite crystals with random compositional segregation. The encoding scheme is mainly based on the number of fluorescence peaks, categorized into four types, resulting in binary encoding results. However, this patent, based on the different numbers of photoluminescence peaks in compositionally segregated pure inorganic perovskite crystals, only provides a "static" encoding result with fixed dimensions, low encoding capacity, and a cumbersome preparation process, greatly limiting its practical application.

[0005] Based on the phenomenon of phase separation of mixed halogen pure inorganic perovskites induced by laser irradiation, the PUF coding response is modulated and updated by adjusting the laser irradiation power, which solves the current "static" status of optics, expands the key size and coding space, and has adjustable size and higher security. Summary of the Invention

[0006] The purpose of this invention is to provide a method for obtaining size-tunable PUFs based on phase separation of mixed halogen pure inorganic perovskites. Utilizing the randomness in the microsphere fabrication process and the phase separation phenomenon of laser irradiation, a fluorescence spectral response with random peak position variations can be achieved. Multiple sets of unclonable keys can be obtained according to encoding rules, and through random combination, a more secure size-tunable PUF is achieved. It possesses unclonable and unpredictable characteristics, making it difficult to forge and tamper with.

[0007] The technical solution of the present invention is as follows:

[0008] A method for obtaining size-tunable perovskite fragments (PUFs) based on phase separation of mixed halogen pure inorganic perovskites is characterized by the following steps:

[0009] Step 1: Obtain mixed halogen pure inorganic perovskite microspheres;

[0010] Step 2: Randomly select and array scan the mixed halogen pure inorganic perovskite microspheres using a continuous wave laser, and encode the collected fluorescence response into a key;

[0011] Step 3: Adjust the power density of the continuous wave laser and scan the mixed halogen pure inorganic perovskite microspheres in the same region to obtain independent keys under different laser intensities;

[0012] Step 4: Randomly combine the obtained multiple independent keys to obtain a PUF with adjustable size.

[0013] Further, step 1 specifically involves: by controlling the reaction time of halide ion exchange to 10–30 min, a two-step chemical vapor deposition method was used to obtain mixed halogen pure inorganic perovskite microspheres, wherein the mixed halogens are bromine and iodine. The position, size, and bromine-iodine ratio of the mixed halogen pure inorganic perovskite microspheres exhibit random distribution characteristics.

[0014] The density of mixed halogen-pure inorganic perovskite microspheres on the substrate surface was randomly distributed in the range of 0.03–0.10 μm / s. 2 Under small spot irradiation, the number of microspheres covered by the laser spot follows a Poisson distribution, providing a theoretical basis for describing and controlling the statistical properties of optical PUF.

[0015] The size of the mixed halogen-pure inorganic perovskite microspheres ranged randomly from 0.2 to 1.8 μm, and this random size distribution provided a basis for the random distribution of the bromine-iodine ratio in the cesium lead halide-pure inorganic perovskite. The bromine-iodine elemental ratio ranged randomly from 0.47 to 10.2, and the fluorescence peak position ranged from 525 to 695 nm.

[0016] Further, the encoding process in step 2 specifically involves: counting the wavelengths of the strongest peaks of all spectral lines, and defining the median of the strongest peak wavelengths as the threshold wavelength. Bits with a strongest peak wavelength less than the threshold wavelength are assigned a value of 0, while bits with a strongest peak wavelength greater than or equal to the threshold wavelength are assigned a value of 1. Once the determination is complete, the binary key is obtained.

[0017] The power density of the continuous wave laser ranges from 0.017 to 3.37 W / cm². 2 Among them, 0.017~0.168W / cm 2 It falls within the low power density range, 0.168–3.37 W / cm². 2 It is in the high power density range.

[0018] The working principle of this invention is as follows:

[0019] Under ambient temperature (room temperature, humidity below 40%, standard atmospheric pressure), laser irradiation at specific wavelengths (above the material's band gap) with multiple power densities produces different results: When irradiating mixed halogen-pure inorganic perovskite microspheres with lasers in the low power density range, the low-power laser does not cause phase separation or the degree of phase separation is so small as to be undetectable. The randomness of the microspheres' density, position, size, and bromine-iodine ratio results in random characteristics in the fluorescence response. However, when irradiating mixed halogen-pure inorganic perovskite microspheres with lasers in the high power density range, due to the occurrence of phase separation, the fluorescence peak positions of the pure inorganic perovskite microspheres with different bromine-iodine ratios will exhibit different degrees of redshift. By adjusting the laser power density to irradiate the same array, multiple independent binary keys can be obtained. By randomly combining these keys, a size-adjustable PUF with higher security can be achieved.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. The fabrication process of microspheres is uncontrollable, with their density, position, size, and bromine-iodine ratio exhibiting random distribution characteristics. Even if the fabrication method is fully disclosed, it is difficult to accurately replicate the microspheres under the same conditions or using high-precision processing technologies such as 3D printing. Furthermore, the spectral response is difficult to predict and attack using deep learning algorithms.

[0022] 2. Mixed halogen-pure inorganic perovskite microspheres undergo phase separation under high-power-density laser irradiation, resulting in spectral lines that differ from those under low-power-density laser irradiation. By adjusting the laser irradiation intensity, independent binary encoding results are achieved. Random combinations of these encodings yield size-adjustable perovskite fairings (PUFs), significantly improving the security of information response.

[0023] 3. The phase separation phenomenon of mixed halogen pure inorganic perovskite microspheres is achieved by irradiation with continuous wave laser. Continuous wave laser has high stability, low power consumption and miniaturization characteristics, making it more suitable for practical application scenarios.

[0024] 4. The preparation process is simple, and a uniform binary distribution can be achieved without the need for debiasing algorithms on the response spectrum, thus avoiding the loss of effective degrees of freedom. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method for obtaining size-tunable PUF based on the separation of pure inorganic perovskite phases with mixed halogens according to the present invention;

[0026] Figure 2 This is a schematic diagram illustrating the different responses obtained by irradiating samples with different laser power densities according to the present invention;

[0027] Figure 3 This refers to the bromine-iodine ratio distribution of microsphere a in this invention;

[0028] Figure 4 This is the bromine-iodine ratio distribution of microsphere b in this invention;

[0029] Figure 5 This refers to the bromine-iodine ratio distribution of microsphere c in this invention;

[0030] Figure 6 The difference in microsphere density in this invention;

[0031] Figure 7 This refers to the microsphere size distribution in this invention;

[0032] Figure 8 This is the photoluminescence spectrum of randomly distributed fluorescence peaks in this invention;

[0033] Figure 9 The fluorescence peak position of a single microsphere under high and low power density laser irradiation in this invention;

[0034] Figure 10 This invention presents 20×20 binary keys obtained from high and low power density laser irradiation and their similarity, where a and b are the keys obtained from high and low power density laser irradiation, respectively, c is the similarity graph of the two keys, and d is the distribution graph of the similarity between the two keys.

[0035] Figure 11 This is the result of combining high- and low-power binary keys in this invention; Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments and accompanying drawings, but this should not be construed as limiting the scope of protection of the present invention.

[0037] Please see Figure 1 , Figure 1 This is a flow chart of the size-tunable PUF based on mixed halogen pure inorganic perovskite phase separation according to the present invention. A schematic diagram of the size-tunable PUF based on mixed halogen pure inorganic perovskite phase separation is shown below. Figure 2 As shown in the figure, the results of low-power-density irradiation differ from those of high-power-density irradiation. The method includes the following steps:

[0038] 1. By controlling the reaction time of halide ion exchange to 15 min, mixed halogen pure inorganic perovskite microspheres were obtained by a two-step chemical vapor deposition method. The mixed halogens were bromine and iodine.

[0039] 2. The sample was characterized by scanning electron microscopy, and the density and bromine-iodine ratio of the microspheres were compared. The size distribution and density distribution of the microspheres were analyzed using ImageJ.

[0040] 3. A beam with a spot diameter of 5 μm and a power density of 0.017–3.37 W / cm² was used. 2 A continuous-wave laser with a wavelength of 405nm was first used with a power density of 0.017W / cm². 2 A laser beam was used to randomly select regions of the mixed halogen pure inorganic perovskite microspheres and scan them in a 20×20 array to obtain the fluorescence response of the array.

[0041] 4. After peak finding and threshold selection of the obtained fluorescence response, the strongest peak wavelength of each spectral line is statistically analyzed, and the threshold wavelength is defined as the median of the strongest peak wavelengths of all spectral lines. The relationship between the strongest peak wavelength of each spectral line and the threshold wavelength is determined: points where the strongest peak wavelength of the response spectral line is less than the threshold wavelength are determined as 0, and points where the strongest peak wavelength of the response spectral line is greater than or equal to the threshold wavelength are determined as 1. The binary key is obtained after the determination is completed.

[0042] 5. Adjust the intensity of the continuous wave laser to 3.37 W / cm². 2 The same 20×20 array was scanned again to obtain the fluorescence response at the corresponding power density. Step 4 was repeated for the fluorescence response spectrum to obtain the fluorescence response at 3.37 W / cm². 2 Binary key for power density.

[0043] 6. Concatenate the two independent key combinations to obtain a PUF with adjustable size.

[0044] like Figure 3-5 As shown, the bromine-iodine ratios of three microspheres in a randomly selected area on the sample surface are different, with ratios of 3.92, 2.1, and 0.47, respectively.

[0045] like Figure 6 As shown, the microsphere density differs between two randomly selected regions on the sample surface, with values ​​of 0.03465 μm. -2 and 0.10332μm-2 When irradiated with lasers using the same parameters, the number of microspheres irradiated in the two regions is different, and different fluorescence peaks can be observed.

[0046] like Figure 7 As shown, the microspheres in randomly selected areas on the sample surface are randomly distributed between 0.2 and 1.8 μm in size. The preparation process makes it easier for smaller microspheres to exchange ions. Under the same experimental conditions of laser irradiation, new changes in the fluorescence peak position can be observed.

[0047] like Figure 8 As shown, the combined effect of the above-mentioned random factors leads to the randomness of the observed fluorescence peak position, with the fluorescence peak range being 525–695 nm.

[0048] like Figure 9 As shown, a single microsphere randomly selected from the sample surface is subjected to a low power density of 0.017 W / cm². 2 At this power level, no phase separation occurs or the phase separation rate is too low to be detected during laser irradiation; however, at a high power density of 3.37 W / cm², irradiation with a laser at this power density is also possible. 2 At that time, due to the occurrence of phase separation, fluorescence peaks different from those obtained by low power density laser irradiation appear.

[0049] like Figure 10 As shown, randomly selected areas of the sample were treated with 0.017 W / cm². 2 and 3.37W / cm 2 A 20×20 dot matrix was scanned using laser irradiation at high power density. The 20×20 dot matrix was treated as 20 strings, each with 20 characters. Two independent keys were obtained according to the defined encoding rules, with a similarity of approximately 50%.

[0050] like Figure 11 As shown, Figure 10 The resulting combination of two binary keys increases the key size to 40 bits per string, expanding the encoding capacity. Since the two sets of keys were obtained under different conditions, the security of the combined key is significantly improved.

[0051] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, such as the combination of technical features between embodiments, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for obtaining size-tunable PUFs based on mixed halide pure inorganic perovskite phase separation, characterized in that The method comprises the following steps: Step 1: obtain mixed halogen pure inorganic perovskite microspheres by two-step chemical vapor deposition method through controlling the reaction time of halogen ion exchange of 10 ~ 30 min; the mixed halogen is bromine element and iodine element; the mixed halogen pure inorganic perovskite microspheres have random distribution characteristics of position, size and bromine-iodine ratio: the random distribution range of the substrate surface density is 0.03 ~ 0.10 / μm 2 , the random distribution range of the size is 0.2 ~ 1.8 μm, the random distribution range of the bromine-iodine element ratio is 0.47 ~ 10.2, and the fluorescence peak position range is 525 ~ 695 nm; Step 2: The power density range of 0.017 ~ 3.37 W / cm 2 Continuous wave laser randomly selects and array scans the mixed halogen pure inorganic perovskite microspheres, and encodes the collected fluorescence response as a key. Step 3: adjust the power density of the continuous wave laser to 0.168 ~ 3.37 W / cm 2 In the high power density interval, the array scanning is performed again in the same region as the selected region in step 2, and independent keys are obtained under different laser intensities. Step 4: obtaining a size-adjustable PUF by randomly combining the obtained multiple groups of independent keys.

2. The method of claim 1, wherein the size-tunable PUF is obtained based on a mixed halide pure inorganic perovskite phase separation. The encoding process is specifically as follows: The strongest peak wavelength of all the fluorescence response spectra is counted, and the median of the strongest peak wavelength is defined as the threshold wavelength; The point position with the strongest peak wavelength of the fluorescence response spectrum less than the threshold wavelength is determined as 0, and the point position with the strongest peak wavelength of the fluorescence response greater than or equal to the threshold wavelength is determined as 1; The binary key is obtained after the determination is completed.

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