title: Periodic nanoripples in the surface and subsurface layers in ZnO irradiated by femtosecond laser pulses.
abstract: We present the formation of periodic ripples in ZnO crystal irradiated by a wavelength-tunable femtosecond laser. The results indicate that in the surface thin layer, the periods change from 0.1 lambda to lambda with laser fluences and pulse numbers, and in the subsurface layer the periods are always lambda/2n, where n is the refractive index. The formation processes and mechanisms are also discussed.
authors.affiliation: State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University,Shanghai 200062, China.
authors.forename: X
authors.initials: X
authors.lastname: Jia
authors.forename: T Q
authors.initials: TQ
authors.lastname: Jia
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: P X
authors.initials: PX
authors.lastname: Xiong
authors.forename: D H
authors.initials: DH
authors.lastname: Feng
authors.forename: Z R
authors.initials: ZR
authors.lastname: Sun
authors.forename: J R
authors.initials: JR
authors.lastname: Qiu
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Xu