title: Surface degeneration of W crystal irradiated with low-energy hydrogen ions.
abstract: The damage layer of a W (100) crystal irradiated with 120 eV hydrogen ions at a fluence of up to 1.5 × 10(25)/m(2) was investigated by scanning electron microscopy and conductive atomic force microscopy (CAFM). The periodic surface degeneration of the W crystal at a surface temperature of 373 K was formed at increasing hydrogen fluence. Observations by CCD camera and CAFM indicate the existence of ultrathin surface layers due to low-energy H irradiation. The W surface layer can contain a high density of nanometer-sized defects, resulting in the thermal instability of W atoms in the surface layer. Our findings suggest that the periodic surface degeneration of the W crystal can be ascribed to the lateral erosion of W surface layers falling off during the low-energy hydrogen irradiation. Our density functional theory calculations confirm the thermal instability of W atoms in the top layer, especially if H atoms are adsorbed on the surface.
authors.affiliation: School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, People's Republic of China.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Fan
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031, P. R. China.
authors.forename: Yuwei
authors.initials: Y
authors.lastname: You
authors.affiliation: School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, People's Republic of China.
authors.forename: Weiyuan
authors.initials: W
authors.lastname: Ni
authors.affiliation: School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.affiliation: School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, People's Republic of China.
authors.forename: Lu
authors.initials: L
authors.lastname: Liu
authors.affiliation: Faculty of Electrical Engineering and Media Technology, Deggendorf Institute of Technology, Deggendorf 94469, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Benstetter
authors.affiliation: School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, People's Republic of China.
authors.forename: Dongping
authors.initials: D
authors.lastname: Liu
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031, P. R. China.
authors.forename: Changsong
authors.initials: C
authors.lastname: Liu