オノダ　ジョウ   小野田　穣    所属   福岡教育大学  教育学部 理科教育研究ユニット    職種   講師
言語種別	英語
発行・発表の年月	2010/07
形態種別	研究論文
査読	査読あり
標題	STEM observation of tungsten tips sharpened by field-assisted oxygen etching
執筆形態	共著
掲載誌名	Surface Science
掲載区分	国外
出版社・発行元	Elsevier
巻・号・頁	604,pp.1094-1099
総ページ数	6
担当区分	筆頭著者,責任著者
著者・共著者	Jo Onoda, Seigi Mizuno, Hiroki Ago
概要	Tungsten tips oriented toward the <111> direction were fabricated by field-assisted O2 etching, and observed by means of scanning transmission electron microscopy (STEM) and field ion microscopy (FIM). The radii of curvature of the tip apexes were sharpened from 16–20 nm to less than 2 nm. The O2 etching is considered to start from the O2 imaging region depending on the field distribution around the tip apex and shank. We estimated the effect of field distribution derived from a shank shape and applied bias voltage. The results showed that the tip with a cylindrical shank before the O2 etching became sharper than tips having an initial paraboloidal shape, with respective cone angles (defined in Fig. 3) of 58° and 80°. The field emission (FE) patterns of these etched tips became a single spot derived from the W(111) plane, and their opening angles (defined by the full width at half maximum) were 14.4° and 7.8°, respectively.
DOI	10.1016/j.susc.2010.03.019