[1] Dalian Univ Technol, Sch Phys & Optoelect Technol, Dalian 116024, Peoples R China
[2] Dalian Univ Technol, Key Lab Mat Modificat Laser Ion & Elect Beams, Minist Educ, Dalian 116024, Peoples R China
[3] Univ Siegen, Inst Mat Engn, D-57076 Siegen, Germany