Surface smoothening and compaction of silica glass under dynamic negative ion mixing N. Okubo a, * , Y. Takeda b , H. Amekura b , J.P. Zhao c , V.T. Gritsyna d , N. Kishimoto b a Institute of Materials Science, University of Tsukuba, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan b National Research Institute for Metals, Tsukuba, Ibaraki 305-0047, Japan c Shanghai Institute for Metallurgy, Shanghai 200050, People's Republic of China d Kharkov National University, Kharkov 310077, Ukraine Abstract A dynamic mixing method has been developed to fabricate thick insulator ®lms containing metal nanoparticles. The fabrication process consists of negative ion mixing/implantation and vacuum deposition of the matrix material. Neg- ative Cu ions of 60 keV irradiated a silica substrate at a dose rate 5±30 lA/cm 2 and a simultaneous evaporation of silica glass, at an evaporation rate 0.2±0.4 nm/s, produced thick ®lms up to 500 nm. The surface of the samples was greatly smoothened by the dynamic negative-ion mixing DNIM) method, as compared to that of evaporated ®lms without ion irradiation. The frequency of the Si±O±Si stretching vibration mode of the DNIM samples became smaller than that of the silica glass substrates. Optical absorbance of the samples, particularly around Cu plasmon resonance, was signif- icantly dependent on the Cu dose rate. The results indicate that the ion co-irradiation induces not only surface smoothening but also a compact network of the SiO 2 matrix. Ó 2001 Elsevier Science B.V. All rights reserved. PACS: 41.75.C; 68.55.L; 61.80; 78.20 Keywords: Negative ion; Dynamic ion-beam mixing; Surface smoothening; Metal nanoparticles; Optical properties 1. Introduction Application of negative ion implantation, alle- viating surface charging, demonstrated a high ef- ®ciency of atomic retention in insulating substrates [1]. By using this merit, we have developed a new dynamic ion-mixing method with negative ions to meet ion-assisted fabrication of insulating ®lms. The dynamic negative-ion mixing DNIM) [2] employs intense heavy ions to inject atoms, as well as electron-beam evaporation to grow the matrix. Dynamic ion-beam mixing DIBM) generally has been applied for modi®cation of material surfaces and interfaces [3±5]. In the common dynamic mixing, excess point defects are introduced by light-ion bombardment and consequently the non- equilibrium diusion intermixes surfaces and in- terfaces. The dynamic mixing has succeeded in improving adhesion of surfaces and interfaces or Nuclear Instruments and Methods in Physics Research B 175±177 2001) 663±667 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +81-298-59-5049; fax: +81- 298-59-5027. E-mail address: nari@nrim.go.jp N. Okubo). 0168-583X/01/$ - see front matter Ó 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X  0 1 ) 0 0 3 4 4 - 5