發明所屬之技術領域 本發明係關於一種太陽能選擇性吸收膜構造，尤其有 關一種太陽能選擇性吸收膜構造包含一單一陶瓷金屬合金 (cermet)薄膜，其中該薄膜通過熱氧化而形成具有由其曝露 表面往深度方向漸漸降低的氧原子百分率（金屬體積百分 率漸增）的部份。 先前技術 陶瓷金屬合金可藉由調變陶瓷中不同的金屬體積分率 而擁有許多有趣的光學性質，目前已廣泛的應用於太陽能 選擇性吸收膜。鎪覆漸變式陶瓷金屬合金於高反射基板 上，可使試片的反射光譜於太陽光波長範圍內有多個破壞 性干涉，獲得非常高的太陽光吸收率0.95及低放射率 0.05。澳洲雪梨大學Zhang等硏究人員於美國專利5523132 發表了新式太陽能選擇性吸收膜結構，此結構包含玻璃基 板/高反射金屬層/高金屬體積分率陶瓷金屬薄膜/低金屬體 積分率陶瓷金屬合金薄膜/陶瓷抗反射層，目前已利用批次 式鍍膜機台大量生產使達到商業化。但製備大面積吸熱板 時，批次式鍍膜機台並不適用。對鍍覆大面積的捲筒對捲 筒（roll to roll)連續式鍍膜製程而言，不論是漸變式陶瓷金 屬合金結構或是Zhang等人發表的新式結構均會使製程趨 於複雜，尤其鍍覆多層膜時需要多個真空腔體更是大幅提 昇了製備成本。漸變式陶瓷金屬合金結構或是Zhang等人 發表的新式結構均需要於表層鍍覆一層約70 nm的陶瓷抗 氧化層，然而濺鍍陶瓷薄膜所需的功率遠遠高於濺鍍金屬 所需的功率，使得製備吸收膜時需要較長的濺鍍時間或是 較大耗電功率。 因此，單層膜的選擇性吸收膜將會是具有低成本與適 合捲筒對捲筒（roll to roll)連續式鍍膜製程大量生產的解 決方案。 發明內容 本發明提出一種太陽能選擇性吸收膜構造，包含：位 於一反射金屬層上的單一陶瓷金屬合金（cermet)薄膜，該薄 膜具有一介於150-400 nm的厚度，其中該薄膜具有由其曝 露表面往深度方向漸漸降低的氧原子百分率。 較佳的，該氧原子百分率漸漸降低的部份具有由80% 氧原子百分率降低至35%的梯度。 較佳的，該氧原子百分率漸漸降低的部份係通過熱氧 化而形成。 較佳的，該單一陶瓷金屬合金的金屬部份係選自A1， Cu，W，不銹鋼，Cr，Ni，Mo, Ti，Co及Au所組成之族群； 及陶瓷部份係選自A1N，Si02, Al2〇3, CuO, W03, CrO，鎳 氧化物，Ti02及鈦氮化物所組成之族群。更佳的，該單一 陶瓷金屬合金爲A1-A1N，且A1的原子百分率爲35-45%及 N的原子百分率爲3-20%，及氧的原子百分率爲60-3 5%。 較佳的，該單一陶瓷金屬合金薄膜對太陽能具有 0.8-0.98的吸收率爲及0.01-0.2的放射率。 本發明揭示一種新的單層太陽能選擇性吸收膜構造之 製備方法，包含下列步驟：鍍覆單層陶瓷金屬合金薄膜於 反射性基板上，該薄膜具有一介於150-400 nm的厚度；再 將基板連同所鏟覆的薄膜於一含氧氣氣氛下做加熱處理以 加速薄膜表面氧化，使薄膜表面金屬部份氧化形成陶瓷結 構，於是獲得一具有由曝露表面往深度方向漸漸降低的氧 原子百分率的單層太陽能選擇性吸收膜構造，該構造對太 陽能具有0.8-0.98的吸收率爲及〇·〇1 _〇·2的放射率。 較佳的，該含氧氣氣氛爲空氣。 較佳的，該熱處理係於300-800°C進行10秒-10分鐘 的時間。 較佳的，該鍍覆是濺鍍。 實施方式 太陽能選擇性吸收膜就是對太陽之輻射能具有良好之 吸收性，而同時只有少量之熱紅外線幅射能離開此太陽能 選擇性吸收膜。此太陽能選擇性吸收膜所吸收之能量大小 及可達之最高溫度，由太陽能選擇性吸收膜對太陽光之吸 收率（α)及其熱紅外線放射率（ε)之比例而決定。當（α/ε) = 1〇 時，T = 612K=340°C。當（α/ε)=1 時，T=343K=70°C。當（α/ε) = 20 時，T=728K=456°C。Τ爲膜的表面溫度。 本發明揭示一種新的單層太陽能選擇性吸收膜構造， 及一種新的單層太陽能選擇性吸收膜構造之製備方法。首 先鍍覆單層陶瓷金屬合金薄膜於反射性基板上，再將基板 於大氣下做加熱處理以加速薄膜表面氧化。表面形成的陶 瓷層可同時視爲良好的抗反射層和抗氧化層，由於氧氣漸 變式的侵入該單層陶瓷金屬合金薄膜，於是可得到具有高 效能表現之金屬體積分率漸變式選擇性吸收膜構造。 本發明的一較佳具體實施方式參考圖一及圖二說明如 下： 1. 於反射金屬層10上鍍覆均質單層陶瓷金屬合金薄膜 20，如圖一所示； 2. 將薄膜置於大氣環境下作熱處理，使薄膜表面金屬部份 氧化以形成陶瓷結構，於是獲得一具有由曝露表面往深 度方向漸漸降低的氧原子百分率的單一陶瓷金屬合金 薄膜結構20a，如圖二所示。 本發明的單層陶瓷金屬合金薄膜於加熱後更趨於熱穩 定狀態，具有良好的熱穩定性；薄膜表面金屬部份漸變式 的氧化形成陶瓷結構，形成具有高效能的金屬體積分率漸 變式選擇性吸收膜結構；及薄膜表面金屬部份氧化形成的 陶瓷結構，可視爲良好的抗反射層與抗氧化層。高熱與氧 氣侵入爲選擇性吸收膜衰壞的一大主因，本發明提出之選 擇性吸收膜因已先行於高熱環境下作熱處理，使其整體結 構與光學性質更趨於熱穩定狀態，擁有相當好的熱穩定性。 實施例1TECHNICAL FIELD The present invention relates to a solar selective absorption film structure, and more particularly, to a solar selective absorption film structure including a single ceramic metal alloy (cermet) film, wherein the film is formed by thermal oxidation to have an exposed surface. The portion of oxygen atomic percentage (metal volume percentage gradually increasing) gradually decreasing in the depth direction. Prior art Ceramic metal alloys have many interesting optical properties by modulating different metal volume fractions in ceramics, and they are now widely used in solar selective absorbing films. Coated with a graded ceramic metal alloy on a highly reflective substrate, the reflection spectrum of the test piece can have multiple destructive interference in the wavelength range of sunlight, and obtain a very high solar absorption rate of 0.95 and a low emissivity of 0.05. Researchers from the University of Sydney, Australia, and others published a new solar selective absorption film structure in US Patent 5523132. This structure includes a glass substrate / high reflective metal layer / high metal volume fraction ceramic metal film / low metal volume fraction ceramic metal alloy. The film / ceramic anti-reflection layer has been mass-produced using batch coating machines to achieve commercialization. However, when preparing large-area heat sinks, batch coating machines are not suitable. For a continuous roll-to-roll coating process with a large area, whether it is a graded ceramic metal alloy structure or the new structure published by Zhang et al., The process will become more complicated, especially for plating. The need for multiple vacuum chambers when coating a multilayer film greatly increases the manufacturing cost. Both the graded ceramic metal alloy structure or the new structure published by Zhang et al. Need to be coated with a ceramic anti-oxidation layer of about 70 nm on the surface. However, the power required for sputtering ceramic films is much higher than that required for sputtering metal. The power makes longer sputtering time or larger power consumption required for preparing the absorbing film. Therefore, the selective absorption film of single layer film will be a solution with low cost and suitable for mass production of roll-to-roll continuous coating process. SUMMARY OF THE INVENTION The present invention proposes a solar selective absorbing film structure, including: a single ceramic metal alloy (cermet) film on a reflective metal layer, the film having a thickness between 150-400 nm, wherein the film has an exposure therefrom. Percentage of oxygen atoms gradually decreasing toward the surface. Preferably, the portion where the percentage of oxygen atoms gradually decreases has a gradient from 80% of the percentage of oxygen atoms to 35%. Preferably, the portion where the percentage of oxygen atoms gradually decreases is formed by thermal oxidation. Preferably, the metal part of the single ceramic metal alloy is selected from the group consisting of A1, Cu, W, stainless steel, Cr, Ni, Mo, Ti, Co, and Au; and the ceramic part is selected from A1N, Si02 , Al2〇3, CuO, W03, CrO, nickel oxide, Ti02 and titanium nitride. More preferably, the single ceramic metal alloy is A1-A1N, and the atomic percentage of A1 is 35-45%, the atomic percentage of N is 3-20%, and the atomic percentage of oxygen is 60-35%. Preferably, the single ceramic metal alloy thin film has an absorptivity of 0.8-0.98 and an emissivity of 0.01-0.2 for solar energy. The invention discloses a new method for preparing a single-layer solar selective absorption film structure, including the following steps: plating a single-layer ceramic metal alloy film on a reflective substrate, the film having a thickness between 150 and 400 nm; The substrate and the coated film are heated under an oxygen-containing atmosphere to accelerate the surface oxidation of the film, so that the metal part of the film surface is oxidized to form a ceramic structure. Thus, an oxygen atomic percentage with a gradually decreasing depth from the exposed surface is obtained. The structure of a single-layer solar selective absorbing film has an absorptivity of 0.8-0.98 for solar energy and an emissivity of 0.001 — 0.2. Preferably, the oxygen-containing atmosphere is air. Preferably, the heat treatment is performed at 300-800 ° C for 10 seconds to 10 minutes. Preferably, the plating is sputtering. Embodiments The solar selective absorption film has good absorption to the radiant energy of the sun, and at the same time only a small amount of thermal infrared radiation can leave the solar selective absorption film. The amount of energy absorbed by the solar selective absorption film and the highest temperature that can be reached are determined by the ratio of the solar selective absorption film's absorption of sunlight (α) and its thermal infrared emissivity (ε). When (α / ε) = 10, T = 612K = 340 ° C. When (α / ε) = 1, T = 343K = 70 ° C. When (α / ε) = 20, T = 728K = 456 ° C. T is the surface temperature of the film. The invention discloses a new single-layer solar selective absorbing film structure and a new method for preparing the same. First, a single-layer ceramic metal alloy film is plated on a reflective substrate, and then the substrate is heated in the atmosphere to accelerate the film surface oxidation. The ceramic layer formed on the surface can be regarded as a good anti-reflection layer and anti-oxidation layer at the same time. Since the single-layer ceramic metal alloy film is gradually invaded by oxygen, a metal volume fraction with a high-performance performance can be obtained. Membrane structure. A preferred embodiment of the present invention is described with reference to FIGS. 1 and 2 as follows: 1. A homogeneous single-layer ceramic metal alloy film 20 is plated on the reflective metal layer 10, as shown in FIG. 1. 2. The film is exposed to the atmosphere. Heat treatment is performed in the environment to oxidize the metal portion of the film surface to form a ceramic structure, and a single ceramic metal alloy thin film structure 20a having a percentage of oxygen atoms that gradually decreases from the exposed surface to the depth direction is obtained, as shown in FIG. The single-layer ceramic metal alloy thin film of the invention tends to be in a thermally stable state after heating, and has good thermal stability; the surface metal portion of the film is gradually oxidized to form a ceramic structure, and a highly efficient metal volume fraction gradual type is formed. The selective absorption film structure; and the ceramic structure formed by the oxidation of the metal part of the film surface can be regarded as a good anti-reflection layer and an anti-oxidation layer. High heat and oxygen invasion are major causes of the degradation of the selective absorption film. The selective absorption film proposed by the present invention has been subjected to heat treatment in a high heat environment, making its overall structure and optical properties more thermally stable. Good thermal stability. Example 1
以丙酮（十分鐘超音波震盪V純水（十分鐘超音波震盪V 異丙醇（十分鐘超音波震盪）/純水（十分鐘超音波震盪）/氮 氣吹乾玻璃基板的程序淸洗一玻璃基板。將玻璃基板置於 真空腔體內，採用鋁靶及以DC濺鍍方式將鋁金屬濺鍍於 該玻璃基板上，腔體內抽至1〇_5 Ton:真空，鋁濺鍍功率 13 0W，時間30分鐘，濺鑛時通入20 SCCM氬氣做爲工作 氣體，工作壓力爲3 mTorr。所獲得的鋁反射金屬層具有約 300 nm的厚度。採用錦耙及氮化鋁耙以RF方式將A1-A1N 共濺鍍於該鋁反射金屬層上，腔體內抽至lx W4 Ton:真 空，其中殘留氧氣做爲濺鍍反應氣體。鋁靶濺鍍功率爲 100W及氮化鋁靶濺鍍功率爲250W，共濺鍍時間15分鐘， 濺鍍時通入40 SCCM氬氣做爲工作氣體，工作壓力爲10 mTorr。所獲得的AhAlN陶瓷金屬合金薄膜具有約250 nm 的厚度。 圖三顯示該A1-A1N陶瓷金屬合金薄膜的AES (Auger spectroscopy)縱深分析，其中橫軸爲濺鍍時間（分鐘）及縱軸 爲原子百分率（atom%)。從圖三可以看出氧的原子百分率 (標示爲01的曲線）除了開始的兩分鐘內急速下降外，其餘 均維持在40%上下變動。 前述具有鋁反射金屬層及A1-A1N陶瓷金屬合金薄膜 的玻璃基板於大氣下以每分鐘13°C的升溫速率加熱至 450°C，於450°C持溫10分鐘，再以每分鐘約25°C的速率 降至室溫，而完成熱氧化處理。 圖四顯示熱氧化處理後該A1-A1N陶瓷金屬合金薄膜 的AES縱深分析，從其中可以看出氧的原子百分率（標示 10 爲01的曲線）從約58%降至42%(濺鍍時間約第16分鐘）。 由於氧的侵入，造成A1-A1N陶瓷金屬合金薄膜中的一部份 鋁被氧化，於是接近其曝露表面部份金屬體積百分率最低 隨著深度方向漸增加。 採用日立公司型號U-4001的5°角絕對反射模組量測 該熱氧化處理後A1-A1N陶瓷金屬合金薄膜的反射率，並計 算出其對太陽輻射的吸收率（α)爲0.88。另以D&SAE meter 測得其對太陽輻射的放射率（ε)爲0.03，α/ε値爲29。 實施例2 使用一淸潔過銅基板進行鋁反射金屬層及Α1-Α1Ν陶 瓷金屬合金薄膜的濺鍍，其中濺鍍的條件均與實施例1相 同，除了 Α1-Α1Ν共濺鍍時間縮短爲12分鐘。所獲得的 Α1-Α1Ν陶瓷金屬合金薄膜亦以相同於實施例1的條件進行 熱氧化處理。實施例2的熱氧化處理後Α1-Α1Ν陶瓷金屬合 金薄膜具有0.93的太陽輻射吸收率（α)，及0.03的太陽輻 射放射率（ε)。 圖示之簡單說明 圖一爲本發明的太陽能選擇性吸收膜構造於熱氧化處 理前的示意剖面圖。 圖二爲本發明的太陽能選擇性吸收膜構造於熱氧化處 理後的示意剖面圖。 圖三顯示於本發明的第一實施例中，熱氧化處理前的 11 A1-A1N陶瓷金屬合金薄膜的原子百分率與深度的關係，其 中標示爲〇1的曲線代表氧的原子百分率；標示爲All的 . 曲線代表鋁的原子百分率；及標示爲N1的曲線代表氮的 原子百分率。 圖四顯示於本發明的第一實施例中，熱氧化處理後的 A1-A1N陶瓷金屬合金薄膜的原子百分率與深度的關係’其 中標示爲〇1的曲線代表氧的原子百分率；標示爲A11的 # 曲線代表鋁的原子百分率；及標示爲N1的曲線代表氣$ 原子百分率。 圖號說明 10..反射金屬層 20..熱氧化處理前的單一均質 · (homogenous)陶瓷金屬合金薄膜 20a·.熱氧化處理後的 單一非均質（inhomogenous)陶瓷金屬合金薄膜Wash the glass with acetone (ten minutes of ultrasonic vibration V pure water (ten minutes of ultrasonic vibration V isopropyl alcohol (ten minutes of ultrasonic vibration)) / pure water (ten minutes of ultrasonic vibration) / nitrogen blow dry the glass substrate. Substrate. The glass substrate is placed in a vacuum cavity, and an aluminum target is used to sputter aluminum metal onto the glass substrate by DC sputtering. The cavity is pumped to 10_5 Ton: vacuum, aluminum sputtering power is 13 0W, For 30 minutes, 20 SCCM argon was used as the working gas during splattering, and the working pressure was 3 mTorr. The obtained aluminum reflective metal layer had a thickness of about 300 nm. The broach and aluminum nitride rake were used to RF A1-A1N is co-sputtered on the aluminum reflective metal layer, and the chamber is pumped to lx W4 Ton: vacuum, where residual oxygen is used as the sputtering reaction gas. The sputtering power of the aluminum target is 100W and the sputtering power of the aluminum nitride target is 250W, a total sputtering time of 15 minutes, 40 SCCM argon was used as the working gas during sputtering, and the working pressure was 10 mTorr. The obtained AhAlN ceramic metal alloy film had a thickness of about 250 nm. Figure 3 shows the A1- AES of A1N ceramic metal alloy film (Auger spectros copy) depth analysis, in which the horizontal axis is the sputtering time (minutes) and the vertical axis is the atomic percentage (atom%). As can be seen from Figure 3, the atomic percentage of oxygen (the curve labeled 01) is rapid within the first two minutes. Except for the drop, the rest are maintained at about 40%. The aforementioned glass substrate with aluminum reflective metal layer and A1-A1N ceramic metal alloy film is heated to 450 ° C at a temperature increase rate of 13 ° C per minute in the atmosphere, and at 450 ° C was held at the temperature for 10 minutes, and then reduced to room temperature at a rate of about 25 ° C per minute to complete the thermal oxidation treatment. Figure 4 shows the AES depth analysis of the A1-A1N ceramic metal alloy film after the thermal oxidation treatment. It can be seen that the atomic percentage of oxygen (the curve marked with 10 as 01) has decreased from about 58% to 42% (sputtering time is about 16 minutes). Part of the A1-A1N ceramic metal alloy film was caused by the invasion of oxygen Aluminum is oxidized, so the volume percentage of the metal near the exposed surface is the lowest and gradually increases with the depth. The 5 ° angle absolute reflection module of Hitachi's model U-4001 is used to measure the A1-A1N ceramic metal alloy after the thermal oxidation treatment. Thin-film Reflectance, and calculated its absorption rate (α) for solar radiation is 0.88. Also measured by D & SAE meter is its emissivity (ε) for solar radiation is 0.03, α / ε 値 is 29. Example 2 The aluminum reflective metal layer and the A1-AlN ceramic metal alloy thin film were sputtered using a cleaned copper substrate. The sputtering conditions were the same as in Example 1, except that the total A1-A1N sputter time was reduced to 12 minutes. The obtained A1-A1N ceramic metal alloy thin film was also subjected to thermal oxidation treatment under the same conditions as in Example 1. The A1-AlN ceramic metal alloy thin film after the thermal oxidation treatment of Example 2 had a solar radiation absorptivity (α) of 0.93 and a solar radiation emissivity (ε) of 0.03. Brief Description of the Drawings Figure 1 is a schematic cross-sectional view of the solar selective absorption film structure of the present invention before the thermal oxidation treatment. Fig. 2 is a schematic cross-sectional view of the solar selective absorbing film structure of the present invention after thermal oxidation treatment. FIG. 3 shows the relationship between the atomic percentage and the depth of the 11 A1-A1N ceramic metal alloy thin film before the thermal oxidation treatment in the first embodiment of the present invention. The curve labeled as 〇1 represents the atomic percentage of oxygen; The. Curve represents the atomic percentage of aluminum; and the curve labeled N1 represents the atomic percentage of nitrogen. FIG. 4 shows the relationship between the atomic percentage and the depth of the A1-A1N ceramic metal alloy thin film after thermal oxidation treatment in the first embodiment of the present invention, wherein the curve labeled as 〇1 represents the atomic percentage of oxygen; # The curve represents the atomic percentage of aluminum; and the curve labeled N1 represents the gas atomic percentage. Description of figure number 10. Reflective metal layer 20. Single homogeneous ceramic metal alloy film before thermal oxidation treatment 20a. Single homogeneous ceramic metal alloy film after thermal oxidation treatment
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