本實驗室近期的研究內容包含了成長/分析奈米材料/奈米複合物，並將其應用在鋰離子電池汲水分解等領域中。經由改良合成石墨烯及金屬氧化物/石墨烯複合材料之實驗方法以及技術，進而使鋰離子電池的性能更加提升。

 

    實際上，我們透過簡單一步驟的高效率節能化學合成法合成SnO2-reduced graphene oxide (SnO2-RGO)奈米複合材料，而最特別的是SnO2奈米顆粒的結晶行為以及氧化石墨烯(graphene oxide)的還原反應是同時發生進行的。實驗過程中加入低濃度還原劑所製備得到的SnO2-RGO奈米複合材料具有較好的電化學性質，在高充放電速率(3200 mA g−1)下仍可維持378 mAh g−1 的電容量；且經過50圈的充放電測試後，仍保有穩定的循環電容量522 mAh g−1 (Appl. Surf. Sci., 413 (2017))。

 

    同樣的，我們透過低溫化學法合成的MnO2-RGO 奈米複合材料，經過50圈的充放電測試後，仍維持相對交告且穩定的電容量660 mAh g-1 (Ceram. Int. 43 (2017) 50-54)。

 

    近年來，矽材是其中一個受到研究學者關注的鋰離子電池負極材料，而我們實驗室近期透過高能機械球摩(high energy mechanical milling)並搭配濕式球摩法(wet milling)的方式，提升材料表面在充放電化成中所形成的SEI膜的性能。進而使得當矽材應用在鋰離子電池負極時，在施予電流200 mA g-1的第一圈充放電中，可以得到高達3439 mAh g-1的電容量；且經過50圈的充放電循環測試後，仍維持極高的電容量2403 mAh g-1。此研究結果發表在國際知名的期刊J. Power Sources中(J. Power Sources, 349 (2017) 111-120)。

 

    由於石化能源的消耗與環境氣候變遷，許多再生能源漸受到重視。其中透過水分解產生氫氣，因為其最高的能量密度、高產能及良好儲能載體外，更是個乾淨、環保，對環境友善的製程，堪稱是現今最具有潛力的再生能源之一。本實驗室利用熱注入法製備金屬硫化物催化劑(MoS2, MoS2-MoO2, MoS2-carbon; SnS, SnS2)，應用於水分解製氫(HER)及產氧(OER)。複合材料MoS2-carbon交層結構及MoS2-MoO2核殼結構之Tafel slope分別為118、129 mV/dec，相對於文獻中MoO2 (352 mV/dec)及本實驗製備的OLA-protected monolayer MoS2 (202 mV/dec)，皆有良好的電催化提升。MoS2-MoO2顯著的效果提升主要是來自MoS2豐富的活性點及MoO2有助於載子傳遞方向的改善，提升了導電性並使催化效果增加；而MoS2-carbon則是因為OLA將MoS2層間距增加，可利用單層模型。單層MoS2及硫缺陷貢獻豐富活性催化點，且交替碳層造成MoS2層間導電性提升。同樣地， SnS2薄膜可應用於光催化產氧的反應上，其電流密度可達0.35 mA/cm2 at 1.2 V vs. RHE，此優秀結果可以歸因於低電荷轉移電阻、高載子密度及合適的能帶位置(Ceramics International, 2017, In press)。

 

    本研究團隊亦藉由熱注入法合成SnS奈米晶體，進一步在低真空下與硫粉進行硫化處理使SnS薄膜相變化成SnS2薄膜，最終將SnS與SnS2薄膜分別應用於光催化水分解之陰極與楊極。硫原子藉由硫化處理插入SnS晶體層與層之間並相變化成SnS2，針對這個現象我們提出了一個重構式成長的機制來解釋此相變過程。這種硫化處理能使SnS2薄膜獲得更高的載子濃度，進而改變光催化水分解之反應機制。經過硫化處理後所得到的SnS2薄膜擁有較窄的空間電荷層、較低的電荷轉移電阻與高載子濃度等特性，因此在1.2 V vs. RHE的偏壓下可量測到光電流0.35mA/cm2。藉由紫外-可見光光譜，循環伏安法，Mott–Schottky等實驗數據，我們解釋了SnS與SnS2薄膜在光催化過程中電解質與能帶、能隙之相對關係與反應機制。我們的研究證實了二維的SnS與SnS2有極大潛力發展成大規模的光催化水分解之材料(Thin Solid Films, 596 (2015), 135–139)。

 

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    Our current research includes the growth/characterization of nanomaterials/nanocomposites for applications in Li ion battery and water splitting. We have developed experimental techniques toward the synthesis of graphene, graphene metal-oxide composites and achieved relatively high performance in Li ion batteries. To be specific, we demonstrate a facile, single step, low temperature and energy efficient strategy for the synthesis of SnO2-reduced graphene oxide (RGO) nanocomposite where the crystallization of SnO2 nanoparticles and reduction of graphene oxide takes place simultaneously by an in situ chemical reduction process. The electrochemical property of the SnO2-RGO composite prepared by using low concentrations of reducing agent shows better Li storage performance, good rate capability (378 mAh g−1 at 3200 mA g−1) and stable capacitance (522 mAh g−1 after 50 cycles). (Appl. Surf. Sci., 2017, Accepted). Similarly, we have also achieved high performance of the MnO2-RGO nanocomposite as an anode in a lithium-ion battery. The composite is synthesized at a low temperature chemical solution reaction, and that shows relatively high/stable specific capacities (660 mAh g-1) after 50 cycles (Ceram. Int. 43 (2017) 50-54). Recently, we have also achieved excellent results in Li ion battery where we have used Si as the anode material prepared by high energy mechanical milling followed by wet milling that enhances the formation of SEI layer. Thus coin cell made of Si conducted at 200 mA g-1 gave the first-cycle capacity based on the mass of Si of 3439 mAh g-1, columbic efficiency of 86.4% and retained capacity of 2403 mAh g-1 after 50 cycles (J. Power Sources, 349 (2017) 111-120).

 

    Hydrogen is one of the most promising renewable energy for production and storage. Thus, one of our ongoing research is the fabrication of metal sulfides and metal oxide-metal sulfide core-shell structures for water splitting. To be specific, we are using hot injection method for preparation of MoS2, MoS2-MoO2 core-shell structures and SnSx (x=1,2). These materials have high potential hydrogen evolution reaction and oxygen evolution reaction. A Tafel slope of 129 mV/dec is obtained for MoS2-MoO2 composite, which is much better than MoS2 (202 mV/dec) and MoO2 (352 mV/dec). The enhanced HER performance is attributed to the abundance active sites from MoS2 and the improved charge transfer direction by MoO2. The enhanced HER performance of MoS2-carbon interoverlapped structure is attributed to the abundance active sites from the interlayer expansion monolayer MoS2 by OLA and many S-defects after carbonization, with the improved conductivity along c-axis by carbon. Similarly, the obtained SnS2 thin films are used as an photocatalysts for OER for the achieve a significantly higher current density of 0.35 mA/cm2 at 1.2 V vs. RHE was achieved which can be attributed to lower charge transfer resistance, high carrier density and a suitable reaction band position (Thin Solid Films, 596 (2015), 135–139).

 

 

 

 

 

    我們對於氧化鋅鎂薄膜在光感測器的應用相當有興趣。藉由磁控濺鍍和成分為Mg0.3Zn0.7O的靶材在矽（111）基板上鍍出品質優良、單相且為纖鋅礦結構的氧化鋅鎂薄膜。在沒有緩衝層的狀態下，此薄膜依舊具有高度朝向c軸的成長方向，並有相似奈米柱狀晶之形貌。為異質結構的氧化鋅鎂／矽屬於金屬－半導體－金屬之光感測器構造，此裝置在2伏特且低發光強度（2.77毫瓦）之325奈米雷射下具有非常高的敏感度（3126 %）(Thin Solid Films, 620[1](2016), 170–174)。

 

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    We have a keen interest in studying the MgxZn1-xO thin films for their applications in photodetectors. We demonstrate the growth of high quality, single phase, wurtzite MgxZn1-xO thin films on p-type Si (111) substrate by magnetron sputtering using Mg0.3Zn0.7O as target. The films are highly oriented along the c-axis and have nanorod like morphology and no buffer layer is used for the growth. The heterostructures of MgZnO/Si are fabricated into metal-semiconductor-metal photodetectors with very high sensitivity (3126 %) at 2 V bias under 325 nm laser at relatively low illumination intensity (2.77 mW) (Thin Solid Films, 620[1](2016), 170–174).

 

 

 

 

 

    本人致力於研究結構陶瓷及其複合材料的製備、微結構分析，以及材料力學性能評估；研究對象涵蓋氧化鋁/A356合金(Al2O3/A356)、氧化鋁-氧化鉻/碳化鉻(Al2O3-Cr2O3 / Cr-carbide)複合材料、碳化矽鬚晶/碳化矽(SiC fiber/SiC)、碳化鈦矽(Ti3SiC2)以及氮化矽基複合材料(Si3N4 matrix composites)等材料；研究主題涵蓋複合材料的界面力學行為、破壞韌性及破壞性檢測，並開發出許多新的陶瓷製程技術，如「有機金屬氣象沉積法 (MOCVD in Fluidized Bed)」，用以製備氧化鋁-氧化鉻/碳化鉻(Al2O3-Cr2O3 / Cr-carbide)奈米複合材料，獲致優異的成果。

 

    於介電及鐵電陶瓷的製備與分析相關研究成果中，發現反晶相界面(Antiphase Boundaries )上的超晶格排列(superlattice modulation) 所形成的超有序結構(extra ordering structure)，是提昇介電陶瓷材料品質因子(Q-factor)的主因，這是一個全新的概念，相關成果已發表於著名國際期刊(Applied Physics Letters 87(2005), 102905)。

 

    本人於「反應鍵結(Reaction Bonded)氮化矽粉末」或「反應鍵結(Reaction Bonded)氮化矽/碳化矽鬚晶複合材料」製備及研究獲致優異的成果，並獲得兩項美國發明專利；此項成果已被許多相關於氮化矽材料的研究者參考及引用。

 

本人亦獲邀編撰三本與結構陶瓷製程及特性相關書籍中的章節，分別為「Advanced ceramics (III) 79.11 (1990) 11, “The effect of microstructure on the properties”」, 「Advanced ceramics (IV) 80.05 (1990) 11」以及「the handbook of ceramics technology - Silicon Nitride structural ceramics (III) Ch.23 (1994).」。

 

    本人主持許多與陶瓷複合材料相關的科技部研究計畫，並將許多基礎研究成果成功技術轉移，這當中包含「以射出成型法製備陶瓷元件」、「氮化矽韌化機制」、「耐磨耗(TiAl)N製備技術」、「製備複雜形狀Cr3C2/Al2O3複合材料元件技術」等，相關成果已發表於著名國際期刊(Journal of the European Ceramic Soc. 23 (2003) 1477-1484) (J, Mater. Res., 18[5] (2003), 1162-1167)。

 

    本人所執行的計畫項目已被公認為是台灣的大學中產學合作的最佳模範之一。 本人亦擔任許多國家科學委員會奈米塗層計畫之主持人，發展化學氣相沉積方法並研發製備氮化鈦coated碳化鈦作為碳化鈦/氮化矽複合材料的表面塗層；另外，也開發了透明導電塗層（TCO） 材料，研發成本效益好的擴散阻障層，SiC介質阻障層，以及將AlN薄膜/ CVD鑽石結構材料應用於SAW濾波器元件中，CsxWO3薄膜則可用於作為近紅外光遮蔽塗層等等。

 

    本人的團隊利用電子束蒸鍍法製備遮蔽紅外光之薄膜。結果顯示CsxWO3薄膜具有高可見光穿透度(70%)以及高紅外光遮蔽率(99%) (Surface & Coatings Technology, 284 (2015), 75–79)。

 

    而紅外光遮蔽材料可應用於太陽能搜集器、智慧窗以及濾光器。紅外光的遮蔽已經藉由於窗戶上之透明隔熱塗層實現。

 

    另外，表面聲波元件(SAW)已被廣泛應用於電子及通訊元件中。隨著第四代行動通訊技術(4G)廣為使用，表面聲波元件操作溫度的範圍及工作頻率也面臨更高的要求。本團隊利用RF及DC雙靶反應性磁控濺鍍，將純氮化鋁(AlN)與掺雜不同鈧含量之氮化鈧鋁(ScxAl1-xN)薄膜成長於類碳鑽/矽基板。實驗結果顯示，當氮化鈧鋁薄膜中鈧的參雜量達到x=30.33%時，壓電係數d33可達到最高值11.54 pC/N，與純氮化鋁薄膜/類碳鑽/矽基板的d33(0.73 pC/N)相比增加了14倍(Surface and Coatings Technology, 308[25] (2016), 101–107)。

 

    為了實現未來高效能光電元件之需求，低電阻率及高透光率的透明電極扮演相當重要的角色。

 

    我們開發出具有低電阻率(~ 10-5 Ω-cm)和在可見光範圍 ( 300 - 800 nm)有高透光率(>80 %)之新型多層透明導電薄膜，像是氧化鋅鋁/金/氧化鋅鋁和氧化鋅鋁/銅/氧化鋅鋁等多層薄膜，該薄膜之光電特性均優於現有的透明導電薄膜。該光電特性是未來許多重要光電技術的關鍵組成部分。本實驗室開發之多層透明導電薄膜相關文章如下，(Materials Science and Engineering B., 186 (2014), (117-121)、(Thin Solid Films, 605 (2016),121-128)、(Ceramics International, 42 [5] (2016), 5754-5761)。這些透明導電薄膜的相關研究在國際期刊上被接受並發表，在研究界得到廣泛的認可和討論。

 

    最後，我們已經成功地將多層透明電極應用於電致變色元件上 (ECD)。 該電致變色元件不僅具有高光學調製性，而且具有IR抑制功能，可同時實現高性能電致變色元件和低輻射玻璃的功能。 由於我們使用AZO / Au / AZO多層結構設計透明電極，並且成功地開發出具有納米晶體結構的WO3電致變色層，因此，具有多層透明電極的電致變色元件可以實現多種電致變色性能，例如快速響應時間(著色：9.9 秒和去色：4.7 秒)、長壽命、高穩定性，高光調製(約80 %)和IR抑制。 該電致變色元件之研究在整個研究領域得到了廣泛的認可，並被引用為可能在評論文章和國際期刊中的一個很好的參考。 (IEEE Electron Devices Letters，36 [3] (2015)，256-258)。

 

    由於奈米結構及奈米材料具有基礎物理學研究的重要性及其潛在應用，因此，引起本研究團隊之研究興趣及熱誠。氧化鋅具有多變性的高品質簡單的形貌，例如：筆型、線型、棒狀、管狀、彈簧狀等等，這些多樣性結構之氧化鋅其實僅須利用低成本熱蒸鍍法、電子濺鍍及合金技術在低溫環境下，不需任何觸媒和極端條件下，即可展現其獨特的維度結構特性，這展現了對於未來在實際應用上的希望曙光！

 

    基於以上這些特性，促使我們無需使用太耗費資源的方法途徑，即可成長出不同形貌的氧化鋅奈米結構，並且能將其應用在場發射、發光及PN街面等多元新穎的元件中，相關成果已發表於著名國際期刊中(Applied Physics Letters, 86 (2005), 251104) (Applied Physics Letters, 87 (2005), 013110) (Applied Physics Letters, 87 (2005), 053103)。

 

    至今，本人的研究範疇主要包含新穎材料、實驗方法和創新技術的開發及應用，並積極研究不同材料的行為表現和反應現象，及其對於科技技術以及實際應用之重要性！

 

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    I conducted studies on fabrication, evaluation and analysis of structural, micro-structural and mechanical properties in Al2O3/A356, Al2O3–Cr2O3 / Cr-carbide nanocomposites, SiC fiber/SiC, Ti3SiC2 and Si3N4 matrix composites etc., interface mechanical behavior of the composites, fracture toughness and damage detection of the composites. I have developed new experimental techniques, such as MOCVD in Fluidized Bed for the processing of Al2O3 – Cr2O3 / Cr-carbide nano-composites and achieved excellent results. My recent work also focused on areas of dielectric and ferroelectric ceramics and processing and fabrication of ceramics. Based on my study on ferroelectric ceramics, I have introduced one new concept of extra ordering structure (superlattice modulation) on the APBs contributed to the improved Q value with the stabilization of ordering-induced domain boundaries (Applied Physics Letters 87(2005), 102905).

 

    I have performed excellent work on the Production and Sintering of Reaction Bonded Silicon Nitride Composites Containing Silicon Carbide Whiskers or Silicon Nitride Powders and granted two US patents. This work has been referenced and quoted by various researchers for the further work on Silicon Nitride. I have also contributed chapters in three books on the processing and properties of structural ceramics, Advanced ceramics (III) 79.11 (1990) 11, “The effect of microstructure on the properties”, Advanced ceramics (IV) 80.05 (1990) 11 and the handbook of ceramics technology - Silicon Nitride structural ceramics (III) Ch.23 (1994).

 

    I have served as a leader of many projects on ceramic composites (1992-2010, NSC Taiwan), and succeeded to transfer fundamental research results such as fabrication of ceramic device using injection forming, high density high toughness AlN/Al component, toughen method for Si3N4, fabrication technique to endure abrasion (TiAl)N, manufacture of complex shaped Cr3C2/Al2O3 components and so on (Journal of the European Ceramic Soc. 23 (2003) 1477-1484) (J, Mater. Res., 18[5] (2003), 1162-1167). My project has been recognized as one of the best models of University-Industry collaboration style in Taiwan. I have also served as a group leader in many Nano-Coating project of National Science Council, Taiwan, to develop chemical gas deposition method of preparing titanium nitride coated titanium carbide for titanium carbide/ Silicon Nitride Composites, development of transparent conducting coating (TCO) materials, development of cost effective improved diffusion barrier, SiC dielectric barrier, AlN films /CVD diamond structure for SAW filter device, and CsxWO3 films for near-infrared shielding coating films etc. My group prepared CsxWO3 films using electron beam evaporation were used as near-infrared shielding thin film. The results show that the NIR shielding properties of CsxWO3 films showed high transmittance of visible light (70%) and high NIR shielding ratio (99%) (Surface & Coatings Technology, 284 (2015), 75–79).

 

    Near-infrared (NIR) light shielding materials have been applied in solar collectors, smart windows, and optical filters. NIR shielding has been achieved by utilizing transparent thermal coatings on windows.

 

    Surface acoustic wave (SAW) devices have been widely applied in electronic and communication systems. With the popularity of fourth generation (4G) mobile communication, the industrial demand for larger operating temperature and frequency filters is drastically increasing. My group report deposition of pure AlN and ScxAl1-xN thin films with different Sc concentration on DLC/Si substrate by RF and DC reactive magnetron co-sputtering method. The piezoelectric coefficient (d33) of ScxAl1-xN thin films are measured and the highest value (11.54 pC/N) is achieved at x = 30.33% increasing 14 times, as that with AlN/DLC/Si, 0.73 pC/N. ScxAl1-xN films on DLC/Si substrate have a great potential to be applied on high frequency SAW devices in the future (Surface and Coatings Technology, 308[25] (2016), 101–107).

 

    In order to fit the demand for high-performance opto-electronic devices, the transparent conducting films of the low resistivity and high transmittance are important role in opto-electronic device applications.

My group developed new multilayer transparent conductive film (TCF) with low resistivity (~ 10-5 -cm) and high transmittance (>80 % in the visible region), such as Al-doped ZnO(AZO)/Au/AZO films and AZO/Cu/AZO films having superior performance than that of existing TCO materials which represents a key component in a number of important opto-electronic technologies. (Materials Science and Engineering B., 186 (2014), 117–121) (Thin Solid Films, 605 (2016), 121–128) (Ceramics International, 42 [5] (2016), 5754–5761). These transparent conductive films related studies were accepted and published in international journals, and they were widely recognized and discussed in the research community.

 

    Final, we have successfully applied multilayered transparent electrodes to electrochromic devices (ECD). The electrochromic devices not only have high optical modulation but also IR-suppression for achieving simultaneously the properties of a high performance electrochromic device and low-E glass. Since we use AZO/Au/AZO multilayer structure to design transparent electrodes and the preparation of nano-crystalline structure of the WO3 electrochromic layer. In addition, the electrochromic devices having the multilayer transparent electrodes can achieve multiple of the electrochromic properties, such as the fast response time (coloration: 9.9 s and bleaching: 4.7 s), long life time, high stability, high optical modulation (optical modulation (ΔT) about 80%) and IR-suppression. The work of this device is well recognized across the research community, and cited as a good reference in may review article and international journals. (IEEE Electron Devices Letters, 36 [3] (2015), 256-258).

 

    The work on nanostructures and nanomaterials of our group stimulated considerable interest for scientific research due to their importance in fundamental physics studies and their potential applications. High quality simple nanostructures having various morphologies of ZnO such as pencils, wires, rods, tubes, springs etc are synthesized using low cost thermal evaporation, electrodeposition and alloying technique at low temperatures without the use of catalyst and extreme conditions and studied their unique structural dimensionality, that showed promising characteristics for practical applications. Without much effort, it can be grown in many different nanostructure forms in different substrate and in free standing form, thus allowing various novel devices in terms of field emission, luminescence and p-n junction (Applied Physics Lettrs, 86 (2005), 251104) (Applied Physics Letters , 87 (2005), 013110) (Applied Physics Letters. 87 (2005), 053103).

 

    Now my research work is mainly involved for the development and application of new materials, tools and innovative technique for the study of materials behavior and phenomena of different ceramic materials for technological importance.