Papers by Keyword: Ripples

Abstract: We study the influence of ripple waves on graphene sheets and graphene nanoribbons. Such waves are originating from the electromechanical effects, among other possible mechanisms. By considering variations in the in-plane and out-of-plane displacement vector, we show that the spontaneous generation of ripple waves has no preferred orientation. Intrinsic properties of ripple waves induce a large pseudopotential that in its turn is to induce large pseudomagentic fields that can be implemented into the band engineering of graphene structures.

Abstract: The study investigates alterations in surface morphology of microcrystalline diamond (MCD) film under reciprocating sliding test conditions. The MCD film was grown by microwave plasma enhanced chemical vapor deposition (MW-PECVD) on (100)-oriented Si wafer. The surface morphology was characterized by optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM) and mechanical profilometry. The formation of ripples on the wear scar surfaces was observed. The normalized wear rate (mm³/mN) of diamond film was evaluated using different approaches in order to understand the influence of diamond film deflection to wear.

Abstract: This paper investigates the morphological modifications of the nanocrystalline diamond (NCD) film surface under reciprocating sliding test conditions. The surface morphology was characterized by atomic force microscopy (AFM). We observed longitudinal grooves and transverse ripples which were formed during the sliding tests on the NCD film surface. The primary goal of the study was to understand the influence of frequency, sliding distance and load variations on the formation of ripple patterns on the wear scars surface. The morphological alteration from continuous to broken ripple shapes was observed. Our study suggests that the geometrical shape of ripples is affected by the formation of the periodic array of grooves.

Abstract: Regular micro-apparatus which covered with periodic nano-hole, nano-ridge and ripple structures on silicon bulk were formed by laser micro-machining with tightly focused beam of the femtosecond laser with wavelength of 800 nm, repetition rate of 1 kHz and the pulse length of 130 fs in air. The periodic nano-hole structures which focus with a 20× focusing objective lens (NA = 0.4) is reported. Investigating the relationship between the width of structures and the speed of processing.

Abstract: Experiments are carried out on a femtosecond laser micromachining system with the wavelength 775nm. The ablated patterns on Si (100) and Si (111) surfaces affected by femtosecond pulse laser parameters are presented. The periodic structure termed ripples on silicon surface is investigated. Two kinds of ripples on the ablated surface are observed by SEM. The whole ablation region indicates the ablated field of all amount of laser energy. The ablation region forms two circular areas. The cross section image of the ablated region is showed which is cut by FIB in the orthogonal direction of the line of the center ripples. The depth of ripples is measured. Adjusted the laser fluence as about 0.3~0.33J/cm2 and the pulse number as changeable from 1 to 50, the forming process of the ripples is observed and studied by AFM. Another experiment is done that the wave-plates are inserted into the space between the objective and sample, the result of the direction of ripples changed with the wave-plates of 1/2 or 1/4 is reviewed.