KR-102963692-B1 - HIGH REFLECTANCE MULTILAYER STRUCTURE AND METHOD OF MANUFACTURING THE SAME

Abstract

Various embodiments provide a high-reflection multilayer thin film structure for obtaining high reflectivity over a wide incident angle and wavelength band, and a method for manufacturing the same. According to various embodiments, the high-reflection multilayer thin film structure may include material layers, each divided into at least three groups having different refractive indices. The material layers may include a plurality of material layers having the same refractive index for each of the groups. The plurality of material layers having the same refractive index may each have different thicknesses that vary aperiodicly depending on their positions in the high-reflection multilayer thin film structure.

Inventors

• 류한열
• 이보해

Assignees

• 인하대학교 산학협력단

Dates

Publication Date

20260512

Application Date

20230207

Claims (13)

1. In a high-reflection multilayer thin film structure, Layers of material each divided into at least three groups having different refractive indices Includes, The above material layers are, It includes a plurality of material layers having the same refractive index for each of the above groups, The above material layers are, It includes a plurality of first material layers having a first refractive index, a plurality of second material layers having a second refractive index lower than the first refractive index, and a plurality of third material layers having a third refractive index lower than the second refractive index, The plurality of material layers having the same refractive index each have different thicknesses that vary aperiodicly depending on their positions in the high-reflection multilayer thin film structure, The above different thicknesses are determined by applying a particle swarm optimization (PSO) algorithm to maximize the average reflectance in the high-reflection multilayer thin film structure, High-reflection multilayer thin film structure.
2. In Article 1, The above material layers are, Non-periodically stacked, High-reflection multilayer thin film structure.
3. In Article 1, The difference between the above different refractive indices is 0.2 or greater, High-reflection multilayer thin film structure.
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5. In Article 1, The above different thicknesses are each 5 nm or more and 500 nm or less, High-reflection multilayer thin film structure.
6. In Article 1, The total number of layers of the above material layers is 10 or more, High-reflection multilayer thin film structure.
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8. In Article 1, The above material layers are, A plurality of additional material layers of at least one group having a refractive index different from the first refractive index, the second refractive index, and the third refractive index Includes more, The additional material layers are stacked non-periodically together with the first material layers, the second material layers, and the third material layers, High-reflection multilayer thin film structure.
9. In Article 1, The above-mentioned high-reflection multilayer thin film structure is applied to at least one of a light-emitting diode or a solar cell, High-reflection multilayer thin film structure.
10. In Article 1, The plurality of material layers having the same refractive index are composed of one of SiO₂ , Si₃N₄ , AlN , Al₂O₃ , TiO₂ , ZrO₂ , MnO, HfO₂ , or Ta₂O₅ . High-reflection multilayer thin film structure.
11. In a method for manufacturing a high-reflection multilayer thin film structure, Step of stacking material layers, each divided into at least three groups having different refractive indices. Includes, The above material layers are, It includes a plurality of material layers having the same refractive index for each of the above groups, The above material layers are, It includes a plurality of first material layers having a first refractive index, a plurality of second material layers having a second refractive index lower than the first refractive index, and a plurality of third material layers having a third refractive index lower than the second refractive index, The plurality of material layers having the same refractive index each have different thicknesses that vary aperiodicly depending on their positions in the high-reflection multilayer thin film structure, The above different thicknesses are determined by applying a particle swarm optimization (PSO) algorithm to maximize the average reflectance in the high-reflection multilayer thin film structure, Method for manufacturing a high-reflection multilayer thin film structure.
12. In Article 11, The above material layers are, Non-periodically stacked, Method for manufacturing a high-reflection multilayer thin film structure.
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Description

High Reflectance Multilayer Thin Film Structure and Method of Manufacturing the Same Various embodiments relate to a highly reflective multilayer thin film structure and a method for manufacturing the same. Generally, distributed Bragg reflector (DBR) structures, which consist of alternating layers of two materials having different refractive indices, are primarily used as optical multilayer thin film structures to achieve high reflectivity. In this case, the two material layers are formed with specific thicknesses, while the material layers with the same refractive index are formed with the same thickness. However, in distributed Bragg reflector structures, reflectivity decreases as the angle of incidence increases—that is, as the angle of incidence deviates from perpendicularity—and the wavelength range in which high reflectivity is maintained also decreases. Consequently, the average reflectivity in distributed Bragg reflector structures is not sufficiently high. Figure 1 is a drawing illustrating a typical dispersed Bragg mirror structure. Figure 2 is a diagram showing the reflection spectrum according to the incident angle of the dispersion Bragg mirror structure of Figure 1. Figure 3 is a diagram showing the average reflectance in the dispersion Bragg reflector structure of Figure 1 for the wavelength spectrum of a typical white LED. FIG. 4 is a drawing illustrating a high-reflection multilayer thin film structure according to a first embodiment. FIG. 5 is a drawing illustrating a high-reflection multilayer thin film structure according to a second embodiment. Figure 6 is a diagram showing the average reflectances in the dispersed Bragg reflector structure of Figure 1 and the high-reflection multilayer thin film structure of Figure 4. Figure 7 is a diagram showing the reflectances according to the incident angle and wavelength in the high-reflection multilayer thin film structure of Figure 4 and the high-reflection multilayer thin film structure of Figure 5, respectively. FIG. 8 is a diagram showing the average reflectances in the fourth high-reflection multilayer thin film structure and the high-reflection multilayer thin film structure of FIG. 5. FIGS. 9a, 9b, 9c, and 9d are drawings illustrating modified examples of a high-reflection multilayer thin film structure according to a second embodiment. FIG. 10 is a drawing illustrating a high-reflection multilayer thin film structure according to a third embodiment. FIG. 11 is a drawing illustrating a high-reflection multilayer thin film structure according to a fourth embodiment. FIG. 12 is a drawing illustrating a method for manufacturing a highly reflective multilayer thin film structure according to various embodiments. Hereinafter, various embodiments of this document will be described with reference to the attached drawings. FIG. 1 is a drawing illustrating a general distributed Bragg reflector structure (DBR) (10). Referring to FIG. 1, a dispersion Bragg mirror structure (10) may include a substrate (11) and material layers (12) stacked on the substrate (11). The material layers (12) may each be divided into two groups having different refractive indices (n H , n L ), and for each of the groups, may include a plurality of material layers ( H , L) having the same refractive index (n H, n L ). In other words, the material layers (12) may include a plurality of first material layers ( H ) having a relatively high first refractive index (n H) and a plurality of second material layers ( L ) having a relatively low second refractive index (n L), and the first material layers (H) and the second material layers (L) may be stacked alternately, that is, periodically. At this time, the first material layers (H) may have a predetermined first thickness, and the second material layers (L) may have a predetermined second thickness. If light having a wavelength of λ0 is incident perpendicularly on such a dispersion Bragg mirror structure (10), a very high reflectance can be obtained when the first thickness and the second thickness are λ0 / 4nH and λ0 / 4nL , respectively. In general, the greater the difference between the first refractive index ( nH ) and the second refractive index ( nL ), and the greater the total number of layers in the dispersion Bragg mirror structure (10), the higher the reflectance in the vertical direction can be obtained. As such, the dispersion Bragg reflector structure (10) has been primarily used as a reflector for laser resonators because it can obtain a high reflectance of 99.9% or more at a specific wavelength and angle of incidence, but recently it is also being used in LED and solar cell structures. In LEDs, light extraction efficiency can be improved by reflecting the light emitted from the active layer that does not escape upwards and travels downwards through the dispersion Bragg reflector structure (10). Meanwhile, in solar cells, efficiency can be improved by reflecting the sunlight that is transmitted without being suffi