Method for regulating and controlling thermal conductivity of crystalline silicon film structure based on phonon interference resonance

Abstract

The invention relates to the technical field of phonon engineering, and provides a method for regulating and controlling the thermal conductivity of a crystalline silicon film structure of phonon interference resonance, which comprises the following steps: constructing a crystalline silicon film phonon interference model structure, and arranging periodically distributed nano-pillar arrays on the surfaces of the two sides of the crystalline silicon film phonon interference model structure as a heat source and a cold source, the period length of the nanorod is set to be adjustable, and a crystalline silicon film model structure containing a periodic heat source and a periodic cold source is obtained; obtaining the dominant phonon wavelength of the crystalline silicon film at the target temperature; adjusting the cycle length of the heat source and the cold source, matching the cycle length with the dominant phonon wavelength of the crystalline silicon film at the target temperature, and inducing multi-channel phonon interference resonance; the thermal conductivity of the crystalline silicon film phonon interference model structure is calculated through unbalanced molecular dynamics simulation, and a thermal conductivity calculation result after regulation and control is obtained; phonon interference and local resonance phenomena are effectively induced by adjusting a periodic nano-point heat source / cold source structure, and a heat conductivity, temperature and length correlation rule is obtained.

Description

Technical Field

[0001] This invention relates to the field of phonon engineering technology, and in particular to a method for controlling the thermal conductivity of a crystalline silicon thin film structure with phonon interference resonance. Background Technology

[0002] With the development of nanofabrication technology, nanostructured materials with characteristic dimensions comparable to phonon wavelengths, mean free path, and coherence lengths have been successfully fabricated, making it possible to control thermal transport through phonon wave properties. Since Anderson and Sabisky discovered the phonon interference effect in the 1970s, an increasing number of researchers have dedicated themselves to adjusting the thermal conductivity of materials through phonon interference. The prerequisite for phonon interference is that phonons retain their phase information during transport, also known as coherent transport. Due to phonon diffusion and scattering, the phase information of high-frequency phonons is easily destroyed; therefore, coherent transport mainly occurs in low-frequency phonons.

[0003] Phonon interference has a dual effect of both reducing and increasing thermal conductivity. In terms of reducing thermal conductivity, it is mainly based on Brillouin zone folding and bandgap formation. Brillouin zone folding directly reduces the phonon group velocity, while bandgap formation filters out phonons of corresponding frequencies. It should be noted that the phonon frequencies involved in thermal transport in nanostructured materials are very wide, ranging from 0.1 THz to tens of THz. The bandgap width is generally limited, so the reduction in thermal conductivity caused by the bandgap is far less than the effect of the phonon group velocity. Regarding increasing thermal conductivity, because phonon interference modifies the phonon spectrum and phonon density of states, it may increase the number of phonon modes that previously contributed significantly to thermal conductivity, or excite phonons that were not previously present. For example, Ju et al. used wave packet dynamics to study the thermal conductivity of composite materials with germanium particles implanted in a silicon matrix. The results showed that the phonon transmittance peaked at a specific germanium particle size, demonstrating the existence of phonon interference and its positive effect on improving thermal conductivity. Jiang et al. conducted wave packet simulation studies on graphene superlattices, indicating that destructive interference between wave packets reflected from the interface can increase phonon transmittance, and full phonon transmission can be achieved by constructing a sufficiently large wave packet space. Unlike the above studies, Zhang et al. constructed a phonon number decay formula, explaining the phonon wave nature contribution from phonon lifetime and coherence time. Their work shows that interference also exists between different phonon wave packets, which prolongs the phonon lifetime and reduces the phonon number decay rate, thereby increasing thermal conductivity by 66%.

[0004] Most current research achieves phonon interference through two approaches: induced Bragg scattering and localization. Bragg scattering occurs in periodic structures. When reflected phonons at the second-period interface satisfy the wave-like interference condition, constructive interference occurs between the reflected phonons, creating a band gap that prevents incident phonons of a certain frequency from propagating forward. This correction of the phonon spectrum reduces the phonon group velocity and density of states, leading to a decrease in the material's thermal conductivity. Bragg scattering primarily occurs in phononic crystals, and this has been well-verified in molecular dynamics simulations. Ravichandran et al. also experimentally prepared perovskite superlattices using molecular beam epitaxy, and room-temperature experiments showed that phonons induce interference within short period lengths due to Bragg scattering. Maldovan specifically pointed out the interference effect of phonons in periodic nanostructures and the conditions for the formation of phonon band gaps. Furthermore, Chen indicated that the number of interfaces is also related to the acoustic mismatch between the two materials; the greater the acoustic mismatch, the stronger the interference effect, and the smaller the required number of interfaces. For gas-solid two-dimensional structures, a strong interference effect is often produced with 5 periods, while for silicon-germanium alloys, 10 periods are required. Phonon localization can be mainly divided into local resonance and Anderson localization. Local resonance refers to the resonance effect when the frequency of the incident phonon at a certain frequency is the same as that of the resonator in the system. At this time, the phonon standing wave phenomenon is significant, causing a series of flat bands in the phonon dispersion, resulting in zero group velocity of the incident phonons. The standing wave also produces hybridization effects with other phonons, thereby reducing the thermal conductivity of the material. The induction of phonon local resonance is currently mainly based on two approaches: one is to introduce a resonator. For example, Hussein et al. studied the thermal conductivity of nanothermal metamaterials with cylindrical teeth grown on silicon thin films. Their phonon spectrum not only has flat bands caused by local resonance, which greatly reduces the phonon group velocity, but also hybridization caused by incident phonons and resonant phonons. The combined effect of the two is to reduce the thermal conductivity of the material by more than 50%. Xion et al. constructed a nanothermal metastructure with columnar branches surrounding silicon nanowires to induce phonon local resonance and hybridization effects, effectively reducing the group velocity and mean free path of phonons with frequencies below 4 THz, thus lowering the thermal conductivity of the thermal metastructure. Secondly, they constructed phonon two-path interference. For example, Hu et al. implanted germanium nanoparticles into a silicon substrate, constructing local resonances through destructive interference of phonons via the particles and those bypassing the particles, thereby reducing the material's thermal conductivity. Their wave packet dynamics studies showed that when the number of particles increased to 10, local resonance caused a significant phonon bandgap. Compared to the bandgap formed by Bragg scattering caused by a single path, this two-path local resonance bandgap does not require a strictly periodic structure. Anderson localization of phonons refers to the multiple scattering of phonons by multiple scatterers, with destructive interference between the multiple scattered waves, resulting in the cessation of phonon motion.There are relatively many pathways for inducing phonon Anderson localization. For example, Hu et al.'s research showed that the non-uniform arrangement of pores in porous graphene induces phonon Anderson localization, and when the system length is greater than 200 nm, all coherent phonons are localized. Luckyanova et al. used molecular beam epitaxy to prepare AlAs-GaAs superlattices containing ErAs nanodots at the interface and conducted thermal conductivity tests and theoretical calculations. The results showed that the scattering of high-frequency phonons at the interface narrows the phonon distribution width, and the folding of the Brillouin zone in the superlattice leads to a reduction in the wave vector, thus satisfying the Ioffe-Regel criterion for phonon localization. Liu et al. achieved Anderson localization by constructing non-uniform periodic superlattice structures and by superlattice interface doping, respectively, and explained Anderson localization from the perspective of phonon participation rate. Similar work has been done in other literature, further confirming the successful induction of Anderson localization by showing that the phonon transmittance decreases exponentially with the characteristic length of the system.

[0005] In the phonon band structure diagram, the Bragg scattering bandgap differs from the localized bandgap. The former is a distinct frequency region with no bands entering, while the latter is a relatively narrow frequency range corresponding to an ultraflat band. An ultraflat band means that the group velocity of the corresponding phonon mode approaches zero, thus phonons in the corresponding frequency range (i.e., within the bandgap) cannot propagate.

[0006] In summary, although there are many pathways to induce phonon interference, they are entirely dependent on the material's constituent elements and the external environment (temperature and pressure, etc.). Changes in any of these factors will alter the phonon spectrum, leading to unsuccessful induction. Furthermore, current research often considers only a single factor, failing to clarify the influence of material structural parameters (period length distribution, scatterer size and distribution, porosity, defect type and quantity, etc.) and environmental factors on phonon interference effects and their relationship with thermal transport. For example, Chakraborty et al., in their study of coherent and incoherent phonon transport in superlattices, concluded that temperature alone can result in different outcomes: thermal conductivity increases, decreases, or initially increases and then decreases with increasing temperature. More importantly, most current research induces phonons of specific frequencies, producing very narrow band gaps, with the attenuation of thermal conductivity generally less than an order of magnitude. How to induce more phonon interference effects by adjusting the material's microstructure and thus widen the band gap remains unclear; this is a prerequisite for controlling the thermal conductivity of nanostructured materials through phonon interference effects. As the feature size of materials shrinks to the nanometer level, interesting phenomena occur in phonon transport when the phonon wavelength is comparable to the period of the heat source. Existing studies have simulated that the wavelength of the main thermal phonons in the pristine silicon crystal at room temperature is about 2 nm.

[0007] Therefore, how to adjust the microstructure of nano-silicon thin films to induce more phonon interference effects, and how to regulate the thermal conductivity of nanostructured materials through phonon interference effects, has become an urgent technical problem to be solved. Summary of the Invention

[0008] In view of this, the main objective of the present invention is to provide a method for controlling the thermal conductivity of a crystalline silicon thin film structure to induce more phonon interference resonance, which aims to adjust the thermal conductivity of the nanostructure material.

[0009] To achieve the above objectives, in a first aspect, the present invention provides a method for controlling the thermal conductivity of a crystalline silicon thin film structure based on phonon interference resonance, comprising:

[0010] S1, Construct a crystalline silicon thin film phonon interference model structure, and set a periodically distributed array of nanopillars on both sides of the crystalline silicon thin film phonon interference model structure as a heat source and a cold source, wherein the period length of the nanopillars is set to be adjustable, thereby obtaining a crystalline silicon thin film model structure containing periodic heat sources and cold sources.

[0011] S2, obtain the dominant phonon wavelength of the crystalline silicon thin film at the target temperature; adjust the period length of the heat source and cold source to match the dominant phonon wavelength of the crystalline silicon thin film at the target temperature, and induce multi-path phonon interference resonance;

[0012] S3, the thermal conductivity of the phonon interference model structure of the crystalline silicon thin film is calculated by non-equilibrium molecular dynamics simulation to obtain the calculated result of the regulated thermal conductivity.

[0013] Preferably, S1 includes:

[0014] S101 sets the lattice constant and silicon film thickness of the thermal crystalline silicon, ensuring that the surface of the crystalline silicon film grows along a specific crystal orientation throughout the process.

[0015] Preferably, S1 includes:

[0016] S102, the geometry of the periodic heat source and cold source is defined as a square, the height of the periodic heat source and cold source is set to 3.80nm, the ratio of width to period is 1 / 2, and the duty cycle of the periodic heat source and cold source on the surface of the crystalline silicon thin film is fixed at 25%.

[0017] Preferably, S1 includes:

[0018] S103, set the crystalline silicon thin film phonon interference model structure to be in equilibrium for 1000 ps under a micro-canonical system until the temperature reaches stability, collect the energy exchange between the heat source and the cold source, calculate the function relationship of heat flux with time, and obtain the heat flux density of the crystalline silicon thin film phonon interference model.

[0019] The temperature gradient is obtained by linearly fitting the temperature distribution within the phonon interference model of crystalline silicon thin films.

[0020] Preferably, S2 includes:

[0021] S201, obtain the thermal conductivity values ​​under uniform heat source and uniform cold source conditions;

[0022] The period is set to a range of 2.17-5.42 nm, and the thermal conductivity values ​​of the phonon interference model structure of the crystalline silicon thin film corresponding to the set period are obtained.

[0023] By comparing the thermal conductivity values ​​under uniform heat source and uniform cold source conditions with the thermal conductivity values ​​of the phonon interference model structure of the crystalline silicon thin film with the corresponding set period, the thermal conductivity modulation results are obtained.

[0024] Preferably, S2 includes:

[0025] S202, obtain at least four period-specific values ​​within the period range, and calculate and obtain the phonon state density of the nanopoint heat source corresponding to the at least four specific values;

[0026] The phonon state density of a uniform heat source is obtained, and the phonon state density of the nanopoint heat source with the phonon state density of the uniform heat source at least four specific values ​​of the periodicity is compared with that of the uniform heat source to obtain the result of the periodic point heat source structure controlling the thermal conductivity.

[0027] Preferably, S2 includes:

[0028] S203, calculate the normalized spectral heat flux of the crystalline silicon thin film phonon interference model structure under the specific frequency range of the phonons corresponding to the at least four specific period values, and compare the normalized spectral heat flux, heat flux density and phonon frequency of the crystalline silicon thin film phonon interference model structure under the at least four specific period values ​​to obtain the contribution results of phonons to thermal conductivity in different frequency regions.

[0029] Preferably, S2 further includes:

[0030] S204. Set the temperature gradient interval to 50K, obtain at least three thermodynamic conditions, calculate the thermal conductivity of the crystalline silicon thin film model structure containing periodic heat sources and cold sources under the corresponding at least three thermodynamic conditions, and obtain the temperature-thermal conductivity variation law.

[0031] Preferably, S2 further includes:

[0032] S205, set the temperature gradient interval to 200K, obtain at least three characteristic temperature points, and calculate the thermal conductivity of the crystalline silicon thin film model structure of the heat source and cold source for different periods corresponding to the at least three characteristic temperature points. Compare the difference in thermal conductivity of the crystalline silicon thin film model structure of the heat source and cold source for different periods corresponding to the at least three characteristic temperature points to obtain the temperature-thermal conductivity difference result.

[0033] Preferably, S2 further includes:

[0034] S206, set the thermodynamic conditions to specific values, obtain the thickness values ​​of at least two crystalline silicon thin film model structures containing periodic heat sources and cold sources, calculate and compare the thermal conductivity corresponding to the thickness values ​​of the at least two crystalline silicon thin film model structures containing periodic heat sources and cold sources, and obtain the results of the silicon thin film length-thermal conductivity variation law.

[0035] Secondly, a system for modulating the thermal conductivity of a crystalline silicon thin film structure based on phonon interference resonance is provided, comprising:

[0036] The model building module is used to construct a crystalline silicon thin film phonon interference model structure. Periodically distributed nanopillar arrays are set on both sides of the crystalline silicon thin film phonon interference model structure as heat sources and cold sources. The period length of the nanopillars is set to be adjustable to obtain a crystalline silicon thin film model structure containing periodic heat sources and cold sources.

[0037] An interference control module is used to obtain the dominant phonon wavelength of a crystalline silicon thin film at a target temperature; adjust the period length of the heat source and cold source to match the dominant phonon wavelength of the crystalline silicon thin film at the target temperature, and induce multi-path phonon interference resonance;

[0038] The thermal conductivity verification module is used to calculate the thermal conductivity of the phonon interference model structure of the crystalline silicon thin film through non-equilibrium molecular dynamics simulation, and obtain the calculated thermal conductivity results after adjustment.

[0039] Thirdly, a control device is provided, comprising a processor and a storage device, the storage device being adapted to store multiple program codes, the program codes being adapted to be loaded and run by the processor to perform the above-described method for modulating the thermal conductivity of a crystalline silicon thin film structure by phonon interference resonance.

[0040] Fourthly, a computer-readable storage medium is provided, wherein a plurality of program codes are stored therein, the program codes being adapted to be loaded and run by a processor to perform the above-described method for modulating the thermal conductivity of a crystalline silicon thin film structure by phonon interference resonance.

[0041] The technical solution provided by this invention systematically explores the thermal conductivity modulation mechanism and phonon interference effect of silicon thin films with periodic nanodot heat source / cold source structures. By adjusting the periodic nanodot heat source / cold source structure, phonon interference and local resonance phenomena are effectively induced. The correlation between thermal conductivity and temperature, and the correlation between thermal conductivity and length are investigated and the laws and results are obtained. This further verifies the thermal conductivity modulation mechanism and phonon interference effect of silicon thin films with periodic nanodot heat source / cold source structures. This not only provides new ideas for the design of nanoscale thermal management devices, but also deepens the understanding of the physical mechanism of phonon interference, laying a theoretical foundation for the development of phonon engineering. Attached Figure Description

[0042] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0043] Figure 1 This is a schematic diagram of the structure of the multipath silicon thin film phonon interference model structure disclosed in one or more embodiments of this application;

[0044] Figure 2 This is a schematic diagram of the heat flow rate of energy exchange between the hot bath and cold bath in one or more embodiments of the system disclosed in this application.

[0045] Figure 3 This is a schematic diagram of the temperature gradient disclosed in one or more embodiments of this application;

[0046] Figure 4 This is a schematic diagram illustrating the change in thermal conductivity of silicon nanofilms as a function of the spatial period between a heat source and a cold source, as disclosed in one or more embodiments of this application.

[0047] Figure 5 This is a schematic diagram of the phonon density of states of a nanodot heat source structure with periodic parameters P of 2.17 nm, 2.72 nm, 3.80 nm and 4.89 nm as disclosed in one or more embodiments of this application;

[0048] Figure 6 This is a schematic diagram of the normalized spectral thermal conductivity disclosed in one or more embodiments of this application;

[0049] Figure 7 This is a schematic diagram comparing the phonon participation rates of a periodic hot bath / cold bath and a uniform hot bath / cold bath as disclosed in one or more embodiments of this application.

[0050] Figure 8 This is a schematic diagram illustrating the thermal conductivity at 250K, 300K, and 350K conditions disclosed in one or more embodiments of this application.

[0051] Figure 9 This is a schematic diagram illustrating the thermal conductivity at 300K, 500K, and 700K conditions disclosed in one or more embodiments of this application.

[0052] Figure 10(a) is a schematic diagram of the spectral heat flow at 700K and P=3.80nm disclosed in one or more embodiments of this application;

[0053] Figure 10(b) is a schematic diagram of the cumulative spectral heat flux value of P = 3.80 nm disclosed in one or more embodiments of this application;

[0054] Figure 11 This is a schematic diagram illustrating the thermal conductivity of the 15nm and 30nm system lengths disclosed in one or more embodiments of this application;

[0055] Figure 12 This is one of the flowcharts illustrating a method for controlling the thermal conductivity of a crystalline silicon thin film structure based on phonon interference resonance, as disclosed in one or more embodiments of this application.

[0056] Figure 13 This is a second schematic flowchart of a method for controlling the thermal conductivity of a crystalline silicon thin film structure based on phonon interference resonance, disclosed in one or more embodiments of this application.

[0057] Figure 14 This is the third flowchart illustrating a method for controlling the thermal conductivity of a crystalline silicon thin film structure based on phonon interference resonance, as disclosed in one or more embodiments of this application.

[0058] Figure 15 This is a schematic diagram of a phonon interference resonance crystalline silicon thin film structure thermal conductivity control system disclosed in one or more embodiments of this application. Detailed Implementation

[0059] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and similar expressions used in this specification are for illustrative purposes only. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of indicated technical features. Thus, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0060] Furthermore, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections via an intermediate medium, or internal communication between two components. All technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0061] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0062] Example 1

[0063] To achieve the above objectives, embodiments of the present invention provide a method for controlling the thermal conductivity of a crystalline silicon thin film structure based on phonon interference resonance, as detailed in the appendix. Figures 12-14 Specifically, including:

[0064] S1. Construct a crystalline silicon thin film phonon interference model structure. Set periodically distributed nanopillar arrays on both sides of the crystalline silicon thin film phonon interference model structure as heat sources and cold sources. The period length of the nanopillars is set to be adjustable to obtain a crystalline silicon thin film model structure containing periodic heat sources and cold sources.

[0065] S2, obtain the dominant phonon wavelength of the crystalline silicon thin film at the target temperature; adjust the period length of the heat source and cold source to match the dominant phonon wavelength of the crystalline silicon thin film at the target temperature to induce multi-path phonon interference resonance;

[0066] S3 calculates the thermal conductivity of the phonon interference model structure of crystalline silicon thin films through non-equilibrium molecular dynamics simulation, and obtains the calculated results of the regulated thermal conductivity.

[0067] In some embodiments, S1 includes:

[0068] S101 sets the lattice constant and silicon film thickness of the thermal crystalline silicon, ensuring that the surface of the crystalline silicon film grows along a specific crystal orientation throughout the process.

[0069] In some embodiments, S1 includes:

[0070] S102, define the geometry of the periodic heat source and cold source as a square, set the height of the periodic heat source and cold source to 3.80nm, the ratio of width to period to 1 / 2, and fix the duty cycle of the periodic heat source and cold source on the surface of the crystalline silicon thin film to 25%.

[0071] In some embodiments, S1 includes:

[0072] S103, set the crystalline silicon thin film phonon interference model structure to be in equilibrium for 1000 ps under a micro-canonical system until the temperature reaches stability, collect the energy exchange between the heat source and the cold source, calculate the function relationship of heat flux with time, and obtain the heat flux density of the crystalline silicon thin film phonon interference model.

[0073] The temperature gradient is obtained by linearly fitting the temperature distribution within the phonon interference model of crystalline silicon thin films.

[0074] In some embodiments, S2 includes:

[0075] S201, obtain the thermal conductivity values ​​under uniform heat source and uniform cold source conditions;

[0076] The period was set to a range of 2.17-5.42 nm, and the thermal conductivity values ​​of the phonon interference model structure of the crystalline silicon thin film corresponding to the set period were obtained.

[0077] By comparing the thermal conductivity values ​​under uniform heat source and uniform cold source conditions with the thermal conductivity values ​​of the phonon interference model structure of the crystalline silicon thin film with the corresponding set period, the thermal conductivity modulation results are obtained.

[0078] In some embodiments, S2 includes:

[0079] S202, obtain at least four period-specific values ​​within the period range, calculate and obtain the phonon state density of the nanopoint heat source corresponding to at least four specific values;

[0080] The phonon density of states of a uniform heat source is obtained, and the phonon density of states of a nanopoint heat source with specific values ​​for at least four periods is compared with that of a uniform heat source to obtain the effect of periodic point heat source structure on thermal conductivity regulation.

[0081] In some embodiments, S2 includes:

[0082] S203, calculate the normalized spectral heat flux of the crystalline silicon thin film phonon interference model structure under a specific frequency range corresponding to at least four specific phonon values, and compare the normalized spectral heat flux, heat flux density and phonon frequency of the crystalline silicon thin film phonon interference model structure under at least four specific phonon values ​​to obtain the contribution results of phonons to thermal conductivity in different frequency regions.

[0083] In some embodiments, S2 further includes:

[0084] S204. Set the temperature gradient interval to 50K, obtain at least three thermodynamic conditions, calculate the thermal conductivity of the crystalline silicon thin film model structure containing periodic heat sources and cold sources under the corresponding at least three thermodynamic conditions, and obtain the temperature-thermal conductivity variation law.

[0085] In some embodiments, S2 further includes:

[0086] S205, set the temperature gradient interval to 200K, obtain at least three characteristic temperature points, and calculate the thermal conductivity of the crystalline silicon thin film model structure of the heat source and cold source for different periods corresponding to the at least three characteristic temperature points. Compare the difference in thermal conductivity of the crystalline silicon thin film model structure of the heat source and cold source for different periods corresponding to the at least three characteristic temperature points to obtain the temperature-thermal conductivity difference result.

[0087] In some embodiments, S2 further includes:

[0088] S206. Set the thermodynamic conditions to specific values, obtain the thickness values ​​of at least two crystalline silicon thin film model structures containing periodic heat sources and cold sources, calculate and compare the thermal conductivity of the thickness values ​​of the corresponding at least two crystalline silicon thin film model structures containing periodic heat sources and cold sources, and obtain the results of the silicon thin film length-thermal conductivity variation law.

[0089] Example 2

[0090] To achieve the above objectives, embodiments of the present invention provide a thermal conductivity modulation system for a crystalline silicon thin film structure based on phonon interference resonance. Please refer to the appendix. Figure 15 Specifically, including:

[0091] The model building module is used to construct a phonon interference model structure of crystalline silicon thin film. A periodically distributed array of nanopillars is set on both sides of the phonon interference model structure of crystalline silicon thin film as a heat source and a cold source. The period length of the nanopillars is set to be adjustable to obtain a crystalline silicon thin film model structure containing periodic heat sources and cold sources.

[0092] The interference control module is used to obtain the dominant phonon wavelength of the crystalline silicon thin film at the target temperature; adjust the period length of the heat source and cold source to match the dominant phonon wavelength of the crystalline silicon thin film at the target temperature, and induce multi-path phonon interference resonance.

[0093] The thermal conductivity verification module is used to calculate the thermal conductivity of the phonon interference model structure of crystalline silicon thin films through non-equilibrium molecular dynamics simulation, and to obtain the calculated results of the thermal conductivity after adjustment.

[0094] Example 3

[0095] To achieve the above objectives, embodiments of the present invention provide a simulation method for phonon interference effects in silicon crystal thin films based on molecular dynamics simulations, specifically:

[0096] Models and methods:

[0097] Multipath silicon thin film phonon interference model structure such as Figure 1 As shown. The lattice constant of the crystalline silicon we use is... The silicon thin film thickness D is 15 nm, and the surface of the nanofilm is along the

[100] direction in all simulations. Si nanopillars with square bases are symmetrically arranged on both sides of the nanofilm as its nanothermal and nanocold baths, with a height H of 3.80 nm. The nanopillars are periodically distributed with a period of P and a width of L, where L / P = 1 / 2. The duty cycle of the silicon nanopillars on the silicon thin film surface is fixed at 25%.

[0098] Simulation process:

[0099] This application employs Large-Scale Atomic / Molecular Parallel Simulation (LAMMPS) for molecular dynamics simulations. The simulation time step is set to 1 femtosecond (fs), and interatomic interactions are described using the Stillinger-Weber potential function. Figure 1As shown, periodic boundary conditions (PBCs) were applied to the simulated system in all three spatial dimensions (x, y, and z). Before the formal simulation, the system was first subjected to energy minimization, allowing it to relax to the nearest local energy minimum. Subsequently, the system was brought to thermodynamic equilibrium for 100 picoseconds (ps) under an isothermal-isobaric (NPT) ensemble, followed by an equilibrium process of the same duration under an isothermal-isochoric (NVT) ensemble. Finally, the thermal transport properties of the system, specifically the thermal conductivity parameter, were calculated using non-equilibrium molecular dynamics (NEMD).

[0100] Calculation method:

[0101] This paper uses a Langevin thermostat to maintain the temperatures of the heat source and heat sink at T. hot and T cold T represents the system temperature. The hot water bath temperature T hot and cold bath temperature T cold They are respectively represented as

[0102] T hot =T(1+Δ) (1)

[0103] T cold =T(1-Δ)(2)

[0104] The system was then equilibrated for 1000 ps under the NVE ensemble until the temperature stabilized and a smooth temperature gradient was obtained. The thermal conductivity k can be calculated using Fourier's law. In the simulation system, 12 layers of fixed atoms were placed at each end as boundary constraints; these atoms do not interact with the atoms inside the system. For thermodynamic boundary treatment, 12 layers of atoms were respectively placed inside the fixed regions as a hot bath (high-temperature heat source) and a cold bath (low-temperature heat sink), thus establishing a stable heat flow channel. Heat is conducted from the hot bath to the cold bath along the x-axis, forming a steady-state heat conduction process. To accurately characterize the temperature distribution, the system was discretized along the x-axis into 100 equally spaced statistical units. A one-dimensional temperature field was constructed by statistically analyzing the time-averaged temperature of the atoms in each unit. Based on this spatial temperature distribution, the temperature gradient can be calculated. (i.e., dT / dx), and then the thermal conductivity parameters of the system are calculated using Fourier's law of thermal conductivity. Its heat flux density is defined as:

[0105]

[0106] Where E hot and E coldThese represent the energy obtained from the heat source and the energy obtained from the cold end, respectively. A is the cross-sectional area of ​​the simulated system perpendicular to the heat transfer direction. To determine the thermal conductivity of the thin film, we use the non-equilibrium molecular dynamics (NEMD) method to directly calculate the effective thermal conductivity of the thin film using Fourier's law.

[0107]

[0108] Where J is the external heating flux density, k is the effective thermal conductivity of the nanowire, and dT / dx is the temperature gradient of the thin film between nanostructures along the direction of the external heating flux. PDOS is a simple method and powerful tool for characterizing phonon activity in materials, calculated from the Fourier transform of the velocity autocorrelation function (VACF) of all atoms.

[0109]

[0110] Where PDOS(ω) is the total PDOS at vibration frequency ω, and VCF is...

[0111]

[0112] Where N is the total number of atoms, v i (t) is the velocity vector of particle i at time t, and ω is the vibration frequency. The angle brackets <> denote the total average. Furthermore, the spectral heat flux density of the model was investigated. When the heat flux approaches steady state, the spectral heat flux density at the corresponding location was calculated.

[0113]

[0114] in It is the second-order interatomic force constant. and Let be the discrete Fourier transform velocities of atom i in the α direction and atom j in the β direction, respectively. The sum of the heat fluxes of atoms in the L-group and R-group, divided by the cross-sectional area, represents the spectral heat through the structure, which can be expressed as:

[0115]

[0116] Phonon participation rate (PPR) effectively provides insights into phonon activity, particularly phonon localization effects. PPR at any temperature can be calculated directly from molecular dynamics simulations without lattice dynamics calculations, implicitly encompassing all orders of inharmonic scattering. It is expressed as...

[0117]

[0118] PDOS i (ω) represents the PDOS of the i-th atom with frequency ω, and N represents the total number of atoms.

[0119] Results and Discussion:

[0120] (1) Effect of period length on thermal conductivity

[0121] First, under the set conditions, we collected the energy exchange between the system's hot and cold baths (see...). Figure 2 The heat flux density of the model was obtained by calculating the functional relationship between the heat flux and time using Equation 3. The temperature gradient was obtained by linearly fitting the temperature distribution within the simulation unit (see...). Figure 3 (excluding the nonlinear region surrounding the heat source and cold source).

[0122] Figure 4 The variation of thermal conductivity of silicon nanofilms with the spatial period (P) of the heat source and cold source is illustrated. For reference, the thermal conductivity values ​​under uniform heat source and uniform cold source conditions (red line) are also shown in the figure. It should be noted that the characteristic wavelength of the phonon, the main hot carrier in silicon materials at room temperature, is approximately 2 nm. Within the periodic range covered in this application (P = 2.17-5.43 nm), compared to a uniform heat source system, the periodic heat source / cold source structure induces quantum interference effects of multipath phonon wave packets, including both constructive and destructive interference modes, resulting in a significant modulation of thermal conductivity. Particularly noteworthy is the 41% significant increase in thermal conductivity, reaching 10⁸ W / (m·K), when the heat source period P = 2.17 nm (comparable to the wavelength of the main hot phonon). Similarly, at P = 3.80 nm, the thermal conductivity increases by 10% to 84 W / (m·K). Conversely, under the conditions of P = 1.63 nm, 2.72 nm, and 4.89 nm, the phonon wave packets undergo destructive interference and form local resonance states, resulting in a significant thermal transport suppression effect, which reduces the thermal conductivity to 59.8 W / (m·K), 61.5 W / (m·K), and 60 W / (m·K), respectively, a decrease of about 20%.

[0123] To elucidate the physical mechanism by which periodic point heat source structures modulate thermal conductivity, we calculated the density of phonon states (PDOS) of nanopoint heat source structures with periodic parameters P of 2.17 nm, 2.72 nm, 3.80 nm, and 4.89 nm based on Equation 5. Figure 4As shown, the calculation results indicate that in the low-frequency region (0-5 THz), all periodic structures exhibit higher PDOS values ​​than the uniform heat source, and this value increases monotonically with decreasing period P (i.e., decreasing nanodot feature size L). In the high-frequency region (13-15 THz), the PDOS of the periodic structures is significantly lower than that of the uniform heat source, accompanied by a redshift of the characteristic peak, with the structure at P = 2.17 nm exhibiting the most significant redshift. Similarly, in the mid-frequency region (9-11 THz), a systematic shift of the characteristic peak towards lower frequencies with decreasing period is observed. It is particularly noteworthy that the increase in low-frequency phonon state density means that coherent phonons with longer wavelengths and mean free paths will have more opportunities for quantum interference. This phenomenon provides a crucial physical basis for understanding the anomalous changes (enhancement or suppression) in the thermal conductivity of crystalline silicon thin films under periodic heat source / cold source structures.

[0124] As thermal phonons generated from different heat sources propagate along the heat flow direction (positive x-axis), they interact, producing phonon interference effects. To explain the variation in thermal conductivity, we calculated the normalized spectral heat flow of thin films with different periodic models. Figure 6 The figure shows the normalized spectral heat flux. Normalized spectral heat flux reflects the contribution of phonons at a specific frequency to heat conduction. Therefore, the contribution of phonons at a specific frequency range to thermal conductivity in different periodic models can be compared by calculating the normalized spectral heat flux. As can be seen from the figure, in the low-frequency region (0–5 THz), the spectral heat flux with a period of 2.17 nm is the highest, followed by the spectral heat flux with a period of 3.80 nm, while the spectral heat fluxes with periods of 2.72 nm and 4.89 nm are close. This provides a preliminary explanation for the mechanism of the increase and decrease in thermal conductivity. When the period is 2.17 nm and 3.80 nm, phonons have a higher heat flux density in the low-frequency region, thus exhibiting higher thermal conductivity. When the period is 2.72 nm and 4.9 nm, phonons have a lower heat flux density in the low-frequency region, thus exhibiting lower thermal conductivity. Furthermore, unlike PDOS, the proportion of low-frequency phonons (0–5 THz) at the heat source gradually increases with decreasing heat source period, while the heat flux density in the low-frequency region of the spectral heat flux does not show a monotonically increasing trend with decreasing heat source period. This indicates that the main thermal phonons generated by nanodot heat sources of different periods undergo interference effects after leaving the heat source, thus causing changes in the contribution of low-frequency phonons to thermal conductivity.

[0125] To delve into the microscopic mechanisms underlying changes in thermal conductivity and their phonon transport behavior, we systematically calculated the phonon participation rate for different periodic models based on Equation 10. The phonon participation rate, as a key parameter characterizing the degree of phonon mode localization, effectively reflects the spatial distribution characteristics of collective phonon excitations. For example... Figure 7As shown, in systems with periodic scales of 2.17 nm and 3.80 nm, the low-frequency region (0-5 THz) exhibits a significant enhancement in phonon participation rate. This is attributed to the constructive interference effect of phonon waves at the Brillouin zone boundary, which causes low-frequency phonons to exhibit extended state characteristics, thus significantly increasing their contribution to thermal transport. Notably, when the period is 2.72 nm and 4.89 nm, the low-frequency phonon participation rate shows a significant decreasing trend. This is attributed to the destructive interference-induced localized resonance effect—phonon waves with specific wave vectors coherently cancel each other in the periodic potential field, forming a localized resonance state, leading to a decrease in phonon group velocity and obstruction of thermal transport channels. This phonon bandgap opening mechanism directly weakens the contribution efficiency of low-frequency phonons in the thermal conduction process.

[0126] (2) Effect of temperature on thermal conductivity

[0127] Temperature, as a crucial parameter that cannot be ignored in actual operating conditions, significantly affects the wavelength distribution characteristics of dominant thermal phonons in the model when the temperature field changes. Furthermore, as the above research shows, thermal conductivity can reach its maximum value when the wavelength of the dominant thermal phonons is comparable to the period length. To further analyze the effect of temperature on the modulation of phonon transport properties in silicon thin films by influencing the wavelength of the dominant thermal phonons, this application uses a temperature gradient of 50K to compare and study the changes in thermal conductivity of silicon thin films with periodic heat source / cold source structures under three thermodynamic conditions: 250K, 300K (room temperature), and 350K. This study aims to explore the influence of phonon wavelength changes on phonon interference results (i.e., thin film thermal conductivity). The results are as follows: Figure 8 As shown in the figure, at a temperature of 350 K, the thermal conductivity of the system exhibits a significant peak at the characteristic period of 1.69 nm. As the temperature decreases, the wavelength of the dominant thermal phonon gradually increases according to the relationship λ∝T⁻¹, causing the peak position of the thermal conductivity to shift towards a larger period. This demonstrates the correlation between the thin film thermal conductivity, the wavelength of the dominant thermal phonon, and the period P.

[0128] Furthermore, as a key thermodynamic parameter for regulating the wave-particle duality of phonons, a significant increase in temperature will substantially enhance the particle scattering mechanism of phonons. This application used a temperature gradient interval of 200 K to calculate the thermal transport characteristics at three characteristic temperature points: 300 K (room temperature), 500 K, and 700 K, to investigate the competition mechanism between the wave and particle nature of phonons in the phonon interference effect. Figure 9The thermal conductivity analysis shown indicates that at temperatures of 300 and 700 K, the thermal conductivity of silicon thin films generally decreases with increasing temperature, and the difference in thermal conductivity between different periodic structures gradually converges with increasing temperature. This temperature evolution characteristic originates from the dynamic transformation mechanism of phonon intrinsic properties: in the low-temperature region (300 K), phonon wave nature dominates, exhibiting significant long-range phase coherence and a low Umklapp scattering probability, thus forming efficient heat transport channels. However, in the high-temperature region (500 / 700 K), phonon particle nature is significantly enhanced through an enhanced three-phonon scattering process, leading to an exponential decay of the mean free path and ultimately suppressing the coherent transport capability of phonons. Notably, under significantly increased temperature conditions, the thermal conductivity shows a marked decreasing trend for most period lengths and for uniform heat / cold sources. This can be attributed to the degradation of the high-temperature-induced phonon interference effect; that is, as the phase coherence length shortens due to enhanced particle nature, the sensitivity of phonon wave nature to the periodic characteristics of the structure significantly decreases. However, under specific periodic conditions (T = 700 K, P = 3.80 nm), the thermal conductivity of the material exhibits a significant enhancement effect. To quantitatively analyze the physical mechanism of this abnormal increase in thermal conductivity and elucidate the phonon scattering behavior in silicon thin films, this application calculates the spectral thermal conductivity and cumulative results of a periodic heat source / cold source structure and a uniform heat source / cold source structure at 700 K and P = 3.80 nm. Figure 10a (10b). The results show that, except for the 7.5-9 THz frequency band, silicon thin films with periodic heat source / cold source structures exhibit significantly higher spectral thermal conductivity values ​​than those with uniform heat source / cold source structures in almost all frequency ranges. This phenomenon indicates that, at 700 K, the periodic heat source / cold source configuration can not only effectively promote the ballistic transport of low-frequency phonons but also significantly suppress the scattering effect of high-frequency phonons. Their synergistic effect leads to a substantial increase in the overall thermal conductivity of the material.

[0129] (3) Effect of system length on thermal conductivity

[0130] Figure 11As shown, this application compares the thermal conductivity variations of silicon crystal thin films with thicknesses of 15 nm and 30 nm in an integrated periodic nanodot heat / cold source system at 300 K. Data shows that, with the thermal conductivity remaining essentially constant with the period, the thermal conductivity of the 30 nm silicon film in the first four periods is significantly lower than that of the 15 nm silicon film. However, in the latter four periods, the thermal conductivity of the 30 nm film shows a significant increase compared to the 15 nm film. In the first four periods, with the increase in silicon film thickness, the interference path in the phonon transport process is significantly lengthened, leading to a more pronounced localization phenomenon caused by the phonon resonance effect. This enhanced localization effect significantly increases the phonon scattering probability, resulting in a systematic decrease in the film's thermal conductivity. In the subsequent four growth periods, due to the increase in film thickness and period length, the constraints of elastic scattering and boundary scattering of high-frequency phonons on phonon transport gradually decrease. This weakening of the boundary effect allows for the extension of the phonon mean free path, ultimately leading to an upward trend in the film's thermal conductivity.

[0131] In summary, based on molecular dynamics simulations, this application systematically investigated the thermal conductivity modulation mechanism and phonon interference effect of silicon thin films with periodic nanodot heat source / cold source structures. The results show that, compared to traditional uniform heat source structures, periodic nanodot heat sources can effectively induce phonon interference and local resonance phenomena. At room temperature, when the heat source period is 2.17 nm (matching the wavelength of the dominant hot phonons), the film thermal conductivity significantly increases to 10⁸ W / (m·K). This enhancement effect is attributed to the volume effect of the nanodot heat source promoting low-frequency phonon excitation, phonon constructive interference at a specific period length, and the increased participation of low-frequency phonons. Conversely, when the period is 2.72 nm and 4.89 nm, the thermal conductivity decreases by approximately 20% due to the local resonance effect induced by destructive phonon interference. Temperature-dependent studies revealed that the period corresponding to the maximum thermal conductivity increases with decreasing temperature (i.e., the wavelength of the dominant hot phonons). Furthermore, the dramatic increase in temperature leads to a shift in the phonon transport mechanism from wave-dominated (coherent) to particle-dominated, manifested as an overall decrease in thermal conductivity across the entire period. Notably, periodic heat source / cold source structures, by modulating phonon scattering channels, exhibit superior thermal conductivity compared to uniform heat source / cold source structures for most period lengths. Length-dependent studies reveal that under short-period conditions, increasing silicon film thickness leads to a significant decrease in film thermal conductivity due to enhanced phonon interference paths. Conversely, under long-period conditions, the weakening of phonon interference effects and the significant increase in the phonon mean free path demonstrate a clear positive correlation between thermal conductivity and thickness.

[0132] This application not only provides new ideas for the design of nanoscale thermal management devices, but also deepens the understanding of the physical mechanism of phonon interference, laying a theoretical foundation for the development of phonon engineering.

[0133] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of the present invention.

[0134] Example 4

[0135] This invention also provides a control device. In one embodiment of the control device according to the invention, the control device includes a processor and a storage device. The storage device can be configured to store a program for executing the phonon interference resonance thermal conductivity modulation method for a crystalline silicon thin film structure according to the above-described method embodiments. The processor can be configured to execute the program in the storage device, which includes, but is not limited to, a program for executing the phonon interference resonance thermal conductivity modulation method for a crystalline silicon thin film structure according to the above-described method embodiments. For ease of explanation, only the parts related to the embodiments of the invention are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of the invention. This control device can be a control device device formed by various electronic devices.

[0136] Example 5

[0137] This invention also provides a computer-readable storage medium. In one embodiment of the computer-readable storage medium according to the invention, the medium can be configured to store a program for executing the phonon interference resonance thermal conductivity modulation method for a crystalline silicon thin film structure according to the above-described method embodiments. This program can be loaded and run by a processor to implement the phonon interference resonance thermal conductivity modulation method for a crystalline silicon thin film structure. For ease of explanation, only the parts related to the embodiments of the invention are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of the invention. The computer-readable storage medium can be a storage device comprising various electronic devices. Optionally, in the embodiments of the invention, the computer-readable storage medium is a non-transitory computer-readable storage medium.

[0138] Those skilled in the art will understand that all or part of the processes in the method of the above embodiment of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0139] The above provides a detailed description of the method, system, device, product, equipment, and medium for controlling the thermal conductivity of a phonon interference resonance crystalline silicon thin film structure. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and its core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for controlling thermal conductivity of a crystal silicon thin film structure by phonon interference resonance, characterized in that, The method comprises the following steps: S1, a crystal silicon thin film phonon interference model structure is constructed, and a periodic nano-pillar array is arranged on both sides of the crystal silicon thin film phonon interference model structure as a heat source and a cold source, wherein the period length of the nano-pillar is adjustable, and a crystal silicon thin film model structure containing a periodic heat source and a cold source is obtained; S2, the dominant phonon wavelength of the crystal silicon thin film at a target temperature is obtained; the period length of the heat source and the cold source is adjusted to match the dominant phonon wavelength of the crystal silicon thin film at the target temperature, so as to induce multi-path phonon interference resonance; S3, the thermal conductivity of the crystal silicon thin film phonon interference model structure is calculated by non-equilibrium molecular dynamics simulation, and a regulated thermal conductivity calculation result is obtained.

2. The method of claim 1, wherein the crystal silicon thin film structure is a phonon interference resonator. The S1 comprises: ​ S101, the lattice constant of the hot crystal silicon and the thickness of the silicon thin film are set, and the surface of the crystal silicon thin film grows along a specific crystal direction in all processes.

3. The method of claim 2, wherein the crystal silicon thin film structure is a phonon interference resonant structure. The S1 comprises: S102, the geometric shape of the periodic heat source and the cold source is defined as a square, the height of the periodic heat source and the cold source is set as 3.80 nm, the ratio of the width to the period is 1 / 2, and the fixed duty cycle of the periodic heat source and the cold source on the surface of the crystal silicon thin film is 25%.

4. The method of claim 1, wherein the crystal silicon thin film structure is a phonon interference resonator. The S1 comprises: ​ S103, the crystal silicon thin film phonon interference model structure is set to be in equilibrium for 1000 ps under the microcanonical ensemble, until the temperature reaches stability, the energy exchange of the heat source and the cold source is collected, the function relationship of the heat flux with time is calculated, and the heat flux density of the crystal silicon thin film phonon interference model is obtained; The temperature gradient is obtained by linear fitting the temperature distribution in the crystal silicon thin film phonon interference model.

5. The method of claim 4, wherein the crystal silicon thin film structure is a phonon interference resonant structure. The S2 comprises: S201, the thermal conductivity value under the condition of a uniform heat source and a uniform cold source is obtained; The range of the period is set as 2.17-5.42 nm, and the thermal conductivity value of the crystal silicon thin film phonon interference model structure corresponding to the set period is obtained; The thermal conductivity modulation result is obtained by comparing the thermal conductivity value under the condition of the uniform heat source and the uniform cold source with the thermal conductivity value of the crystal silicon thin film phonon interference model structure corresponding to the set period.

6. The method of claim 5, wherein the crystal silicon thin film structure is a phonon interference resonant structure. The S2 comprises: S202, at least four period-specific values in the period range are obtained, the phonon state density of the nano-point heat source corresponding to the at least four specific values is calculated and obtained; The phonon state density of the uniform heat source is obtained, and the phonon state density of the nano-point heat source of the at least four period-specific values is compared with the phonon state density of the uniform heat source, so as to obtain the thermal conductivity regulation result of the periodic point heat source structure.

7. The method of claim 6, wherein the crystal silicon thin film structure is a phonon interference resonant structure. The S2 comprises: ​ S203, the normalized spectral heat flow of the crystal silicon thin film phonon interference model structure under the phonon specific frequency range corresponding to the at least four period-specific values is calculated, and the normalized spectral heat flow, the heat flux density and the phonon frequency of the crystal silicon thin film phonon interference model structure of the at least four period-specific values are compared, so as to obtain the contribution result of different frequency region phonons to the thermal conductivity.

8. The method of claim 1, wherein the crystal silicon thin film structure is a phonon interference resonant structure. The S2 further comprises: S204, the temperature gradient interval is set as 50 K, at least three thermodynamic conditions are obtained, the thermal conductivity of the crystal silicon thin film model structure containing the periodic heat source and the cold source under the at least three thermodynamic conditions is calculated, and the temperature-thermal conductivity variation law is obtained.

9. The method for controlling the thermal conductivity of a crystalline silicon thin film structure with sub-interference resonance as described in claim 1, characterized in that, The S2 further comprises: S205, setting the temperature gradient interval to 200K, obtaining at least three characteristic temperature points, and calculating the thermal conductivities of the crystal silicon thin film model structures of the heat source and the cold source in different periods corresponding to the at least three characteristic temperature points, comparing the differences of the thermal conductivities of the crystal silicon thin film model structures of the heat source and the cold source in different periods corresponding to the at least three characteristic temperature points, and obtaining a temperature-thermal conductivity difference result.

10. The method of claim 1, wherein the crystal silicon thin film structure is a sub- interference resonance crystal silicon thin film structure. The S2 further comprises: S206, setting the thermodynamic condition to a specific value, obtaining at least two thickness values of the crystal silicon thin film model structures containing periodic heat sources and cold sources, calculating and comparing the thermal conductivities corresponding to the at least two thickness values of the crystal silicon thin film model structures containing periodic heat sources and cold sources, and obtaining a silicon thin film length-thermal conductivity change rule result.

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