• Anti-reflection structures fabricated by direct laser interference technology under different ambiances

      Wang, Dapeng; Yue, Yong; Zhang, Ziang; Li, Dayou; Maple, Carsten; Wang, Zuobin; University of Bedfordshire (IEEE, 2013-08)
      In this paper, we take the strategy of direct laser interference technology to modify the silicon surface under air and sulphur hexafluoride (SF6) gas ambiance conditions. With the investigation of optical properties, the silicon spike structures (known as black silicon) which were fabricated in the SF6 ambiance showed the excellent ability of reducing light reflection with a broadband spectrum. For comparison, well-defined microcone structures were fabricated in the air ambiance. After hydrofluoric (HF) acid wiping off the oxides on the surface, micro cone structures have shown the anti-reflection function as well and its reflective behaviour was dependent on the structural depth relatively. Due to a high impurities concentration of spike structures obtained in the SF6 ambiance, applications of sulphur-doped black silicon would be limited. To obtain large-scale uniform structures, direct laser interference technology in the air ambiance could be an alternative.
    • Both antireflection and superhydrophobicity structures achieved by direct laser interference nanomanufacturing

      Wang, Dapeng; Wang, Zuobin; Zhang, Ziang; Yue, Yong; Li, Dayou; Qiu, Renxi; Maple, Carsten; University of Bedfordshire; Changchun University of Science and Technology; Xi'an Jiaotong-Liverpool University (American Institute of Physics (AIP), 2014)
      Inspired by nature, a number of techniques have been developed to fabricate the bionic structures of lotus leaves and moth eyes in order to realize the extraordinary functions of self-cleaning and antireflection. Compared with the existing technologies, we present a straightforward method to fabricate well-defined micro and nano artificial bio-structures in this work. The proposed method of direct laser interference nanomanufacturing (DLIN) takes a significant advantage of high efficiency as only a single technological procedure is needed without pretreatment, mask, and pattern transfer processes. Meanwhile, the corresponding structures show both antireflection and superhydrophobicity properties simultaneously. The developed four-beam nanosecond laser interference system configuring the TE-TE-TE-TE and TE-TE-TE-TM polarization modes was set up to generate periodic micro cone and hole structures with a huge number of nano features on the surface. The theoretical and experimental results have shown that the periodic microcone structure exhibits excellent properties with both a high contact angle (CA = 156.3°) and low omnidirectional reflectance (5.9–15.4%). Thus, DLIN is a novel and promising method suitable for mass production of self-cleaning and antireflection surface structures.
    • Direct modification of silicon surface by nanosecond laser interference lithography

      Wang, Dapeng; Wang, Zuobin; Zhang, Ziang; Yue, Yong; Li, Dayou; Maple, Carsten (Elsevier, 2013)
      Periodic and quasi-periodic structures on silicon surface have numerous significant applications in photoelectronics and surface engineering. A number of technologies have been developed to fabricate the structures in various research fields. In this work, we take the strategy of direct nanosecond laser interference lithography technology, and focus on the silicon material to create different well-defined surface structures based on theoretical analysis of the formation of laser interference patterns. Two, three and four-beam laser interference systems were set up to fabricate the grating, regular triangle and square structures on silicon surfaces, respectively. From the AFM micrographs, the critical features of structures have a dependence on laser fluences. For a relative low laser fluence, grating and dot structures formed with bumps due to the Marangoni Effect. With the increase of laser fluences, melt and evaporation behaviors can be responsible for the laser modification. By properly selecting the process parameters, well-defined grating and dot structures can been achieved. It can be demonstrated that direct laser interference lithography is a facile and efficient technology with the advantage of a single process procedure over macroscale areas for the fabrication of micro and nano structures.
    • Effects of polarization on four-beam laser interference lithography

      Wang, Dapeng; Wang, Zuobin; Zhang, Ziang; Yue, Yong; Li, Dayou; Maple, Carsten; Changchun University of Science and Technology; University of Bedfordshire (American Institute of Physics, 2013)
      This paper demonstrates that polarization plays an important role in the formation of interference patterns, pattern contrasts, and periods in four-beam interference lithography. Three different polarization modes are presented to study the effects of polarization on four-beam laser interference based on theoretical analysis, simulations, and experiments. A four-beam laser interference system was set up to modify the silicon surface. It was found that the secondary periodicity or modulation was the result of the misaligned or unequal incident angles only in the case of the TE-TE-TM-TM mode. The resulting patterns have shown a good correspondence with the theoretical analysis and simulations.
    • Superhydrophobic dual micro- and nanostructures fabricated by direct laser interference lithography

      Li, Wenjun; Wang, Zuobin; Wang, Dapeng; Zhang, Ziang; Zhao, Le; Li, Dayou; Qiu, Renxi; Maple, Carsten; University of Bedfordshire; Changchun University of Science and Technology (Society of Photo-optical Instrumentation Engineers (SPIE), 2014)
      A method for the fabrication of highly ordered superhydrophobic dual micro- and nanostructures on silicon by direct laser interference lithography (LIL) is presented. The method offers its innovation that the superhydrophobic dual micro- and nanostructures can be fabricated directly by controlling the process of four-beam laser interference and the use of hydrofluoric acid (HF) to wipe off the silica generated during the process. Different laser fluences, exposure durations, and cleanout times have been investigated to obtain the optimum value of the contact angle (CA). The superhydrophobic surface with the CA of 153.2 deg was achieved after exposure of 60 s and immersion in HF with a concentration of 5% for 3 min. Compared with other approaches, it is a facile and efficient method with its significant feature for the macroscale fabrication of highly ordered superhydrophobic dual micro- and nanostructures on silicon.