熱穩態金屬與超導材料奈米針:製備與場發射特性
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2017
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Abstract
本研究以超高真空場離子顯微鏡研究超導材料奈米針的特性。我們使用鈮發展了一套可靠的熱穩態奈米針製程，其針頂分佈形貌為{100}、{310}、{110}、{123} 與{111}面排列而成，且在<100>軸向形成四個{310}面環繞擴張而堆疊的奈米凸起，此結構可作為一個收斂的場發射束使用。經過氖氣或氙氣不同覆量的鋪覆後發現可降低{100}面的功函數，其中使用氖氣可降至最低的功函數條件為5朗繆爾，其值為3.63±0.08 eV，使用氙氣可降至最低的功函數條件為1.7朗繆爾，其值為3.50±0.04 eV，並此最佳條件下均可增加場發射電流的穩定性。此熱穩態的鈮奈米針結構在經過氧氣的場效蝕刻過程後，依然可藉由熱處理而再次重現。最後我們也討論了其他材料系統的熱穩態奈米針特性。
The characteristics of superconducting material nanotip is studied with UHV field ion microscope. We present a reliable method for a niobium tip with the thermally stable configuration of the cap part consists of {100}、{310}、{110}、{123} and {111}. The<100> directional nano-protrusion surrounded by four {310} facets can be used as a self-collimated field electron emitter. After exposing Ne or Xe gas at different coverage, the work function of {100} decreased to minima of 3.50±0.04 eV for Xe (1.7 Langmuir) and 3.63±0.08 eV for Ne (5 Langmuir); moreover, the field emission current stability was enhanced. The thermally stable configuration of Nb nanoemitter can be regenerated by thermal treatment from field-assisted oxygen etching process. Finally, we also discussed the characteristics of other thermally stable nanotip systems.
The characteristics of superconducting material nanotip is studied with UHV field ion microscope. We present a reliable method for a niobium tip with the thermally stable configuration of the cap part consists of {100}、{310}、{110}、{123} and {111}. The<100> directional nano-protrusion surrounded by four {310} facets can be used as a self-collimated field electron emitter. After exposing Ne or Xe gas at different coverage, the work function of {100} decreased to minima of 3.50±0.04 eV for Xe (1.7 Langmuir) and 3.63±0.08 eV for Ne (5 Langmuir); moreover, the field emission current stability was enhanced. The thermally stable configuration of Nb nanoemitter can be regenerated by thermal treatment from field-assisted oxygen etching process. Finally, we also discussed the characteristics of other thermally stable nanotip systems.
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鈮奈米針, 熱穩態形貌, 功函數, 場發射電流, niobium nanotip, thermally stable configuration, work function, field emission current