Medium-long wave infrared wavelength adjustable near-zero dielectric material based on P-type doped cuprous iodide

Abstract

The invention discloses a medium-long wave infrared wavelength adjustable near-zero dielectric material based on P-type doped cuprous iodide, and relates to the technical field of infrared functional materials, and the technical key points are as follows: the dielectric constant real part Re (epsilon) of the material at a specific wavelength of a medium-long wave infrared band (3-15 [mu] m) is-0.5 to + 0.5; and the wavelength can be continuously regulated and controlled by adjusting the hole carrier concentration (1 * 10 < 19 >-1 * 10 < 21 > cm <-3 >). The material has a remarkable nonlinear optical characteristic near a specific wavelength with a near-zero dielectric constant, and is suitable for the fields of infrared stealth, thermal radiation regulation and control and molecular sensing.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared functional materials, and particularly relates to a copper iodide (CuI)-based mid- and long-wave infrared near-zero dielectric material. Background Art

[0002] Epsilon-Near-Zero (ENZ) materials are a class of special electromagnetic media with the real part of the dielectric constant approaching zero. Their properties stem from the matching of the free carrier concentration in the material with the frequency of the incident electromagnetic wave. When the real part of the dielectric constant Re(ε) approaches zero, the electromagnetic wave exhibits unique behaviors such as infinite wavelength stretching, super-coupled transmission, electromagnetic tunneling, and a significant enhancement of the normal component of the electric field in the material, making it important in sub-wavelength waveguides, metamaterial antennas, and on-chip integrated photonic devices. Currently, free carrier-induced plasmonic ENZ materials (such as transparent conductive oxides, heavily doped semiconductors) are the most widely studied systems. According to the Drude model, changing the carrier concentration of the material can cause a shift in the ENZ wavelength. In the transparent conductive oxide system, the carrier concentration of the material can be changed by changing the element doping concentration, thereby achieving the tuning of the ENZ wavelength.

[0003] The Re(ε) near-zero characteristic of existing heavily doped transparent conductive oxide ENZ materials such as ITO and AZO is limited to the near-infrared band (1 - 3 μm). The present invention discovers for the first time that through the regulation of the hole carrier concentration, the γ-phase CuI material can achieve Re(ε)≈0 at any target wavelength in the mid- and long-wave infrared band (3 - 15 μm), breaking through the defect of the limited band in the prior art. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems and provide a mid- and long-wave infrared wavelength tunable near-zero dielectric material based on P-type doped copper iodide.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows: A mid- and long-wave infrared wavelength tunable near-zero dielectric material based on P-type doped copper iodide, including the following key points:

[0006] 1. Tunability in the mid- and long-wave infrared band: By adjusting the hole carrier concentration (1×10 19 ~1×10 21 cm -3 ) of the CuI material, the wavelength λ ENZ at which Re(ε)≈0 can be adjusted throughout the 3 - 15 μm band;

[0007] 2. Crystal structure dependence: Only the γ-phase cubic CuI can achieve the above characteristics, and other phases (such as the β-phase) do not have this performance.

[0008] Compared with the prior art, the beneficial effects of this solution are as follows: The near-zero Re(ε) characteristic of existing heavily doped transparent conductive oxide ENZ materials such as ITO and AZO is limited to the near-infrared band (1-3 μm). The present invention discovers for the first time that through the regulation of the hole carrier concentration, the γ-phase CuI material can achieve Re(ε)≈0 at any target wavelength in the mid- and long-wave infrared band (3-15 μm), breaking through the defect of the limited band of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is the correspondence between the carrier concentration and λ in the embodiments of the present invention ENZ corresponding relationship. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments and drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0011] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0012] Embodiment 1:

[0013] (a) Weigh 40 g of CuI powder and press it into a dense ceramic target by sintering.

[0014] (b) Install the target in step (a) on the RF target position of the magnetron sputtering equipment, and place the cleaned infrared-transparent substrate into the magnetron sputtering deposition chamber. After the vacuum is pumped to 1×10 -4 Pa, argon is introduced until the pressure in the deposition chamber rises to 1 Pa. Subsequently, use the target in step (a) for RF sputtering, with a power of 70 W and a sputtering time of 30 min, to obtain a transparent conductive film with a thickness of about 150 nm on the transparent medium.

[0015] (c) The carrier concentration of the transparent conductive film prepared in this way is 3.11×10 19 cm -3 , as Figure 1 shown, no near-zero dielectric constant wavelength is found.

[0016] Embodiment 2:

[0017] (a) According to the doping ratio of 1 at%, weigh the corresponding CsI and CuI powders, grind them evenly, weigh 40 g and press them into a dense ceramic target by sintering.

[0018] (b) Install the target in step (a) on the RF target position of the magnetron sputtering equipment, and place the cleaned substrate into the magnetron sputtering deposition chamber. After the vacuum is pumped to 1×10 -4 Pa, introduce argon until the pressure in the deposition chamber rises to 1 Pa. Subsequently, use the target in step one for RF sputtering, with a power of 70 W and a sputtering time of 30 min, to obtain a nearly zero dielectric constant thin film with a thickness of about 150 nm on the transparent medium.

[0019] (c) The carrier concentration of the transparent conductive thin film prepared in this way is 6.51×10 19 cm -3 , as Figure 1 shown, the real part curve of its dielectric constant is translated downward compared with Example 1, indicating that the effective adjustment of the dielectric constant has been carried out in the long-wave infrared for this example.

[0020] Example 3:

[0021] The difference between this example and Example 2 is that the doping ratio in step (a) is 2 at%, and the other steps are the same.

[0022] The carrier concentration of the transparent conductive thin film prepared in this way is 1.67×10 20 cm -3 , as Figure 1 shown, its dielectric constant at 4.99 μm is 0, realizing the nearly zero dielectric constant effect in the mid-wave infrared.

[0023] Example 4:

[0024] The difference between this example and Example 2 is that the doping ratio in step (a) is 3 at%, and the other steps are the same.

[0025] The carrier concentration of the transparent conductive thin film prepared in this way is 3.6×10 20 cm -3 , as Figure 1 shown, its dielectric constant at 4.08 μm is 0, realizing the nearly zero dielectric constant effect in the mid-wave infrared.

[0026] Example 5:

[0027] The difference between this example and Example 2 is that the doping ratio in step one is 4 at%, and the other steps are the same.

[0028] The carrier concentration of the transparent conductive thin film prepared in this way is 4.09×10 20 cm -3 , the dielectric constant at 3.43 μm is 0, realizing the nearly zero dielectric constant effect in the mid-wave infrared.

[0029] Example 6:

[0030] Perform a comparative test on the γ phase and the β phase , and the results show that:

[0031] For γ-phase CuI, when the carrier concentration is 1.67×10 20 cm -3 , λ ENZ = 4.99 μm, Re(ε) = 0;

[0032] For β-phase CuI, there is no characteristic of Re(ε)≈0 at the same concentration.

[0033] As Figure 1 shown, a mid- and long-wave infrared wavelength-tunable near-zero dielectric material based on P-type doped cuprous iodide includes the following characteristics: P-type doping of the main material cuprous iodide, adjusting the carrier concentration (3.11×10 19 ~4.09×10 20 cm -3 ), and the corresponding relationship between the carrier concentration and λ ENZ is as follows. When the carrier concentration is 3.11×10 19 cm -3 , the near-zero wavelength of the dielectric function > 15 μm; when the carrier concentration is 6.51×10 19 cm -3 , the near-zero wavelength of the dielectric function is blue-shifted compared to the former; when the carrier concentration is 1.67×10 20 cm -3 , the near-zero wavelength of the dielectric function is 4.99 μm; when the carrier concentration is 3.6×10 20 cm -3 , the near-zero wavelength of the dielectric function is 4.08 μm; when the carrier concentration is 4.09×10 20 cm -3 , the near-zero wavelength of the dielectric function is 3.43 μm; by adjusting the carrier concentration (3.11×10 19 ~4.09×10 20 cm -3 ), the adjustment of the near-zero wavelength of the dielectric function in the mid- and long-wave infrared band (3 - 15 μm) is realized.

[0034] The above specific embodiments are only explanations of the present invention, and they are not limitations of the present invention. Those skilled in the art can make modifications without creative contributions to this embodiment after reading this specification, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A mid- and long-wave infrared wavelength tunable near-zero dielectric material based on P-type doped cuprous iodide, characterized in that: The real part Re(ε) of the dielectric constant of the said material at specific wavelengths in the mid-wave and long-wave infrared band (3 - 15 μm) is -0.5 to +0.5; the said specific wavelengths are continuously regulated by adjusting the hole carrier concentration of the material (1×10 19 ~1×10 21 cm -3 ).

2. The mid- and long-wave infrared wavelength tunable near-zero dielectric material based on P-type doped cuprous iodide as claimed in claim 1, wherein: The specific wavelength λ ENZ The relationship with the carrier concentration n satisfies the Drude model: where c is the speed of light, e is the electron charge, ε0 is the vacuum permittivity, and m * is the effective mass of the carrier, and ε ∞ is the high-frequency permittivity.

3. A mid- and long-wave infrared wavelength tunable near-zero dielectric material based on P-type doped cuprous iodide, characterized in that: The material has a γ-phase cubic crystal structure with a lattice constant The p-type doping element is one or more of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), oxygen (O), sulfur (S), selenium (Se), and tellurium (Te), and the element doping concentration is 1-5 at%.

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