• Direct metal transfer printing on flexible substrate for fabricating optics functional devices

      Jiang, Yingjie; Zhou, Xiaohong; Zhang, Feng; Shi, Zhenwu; Chen, Linsen; Peng, Changsi; Soochow University (SPIE, 2015-12-31)
      New functional materials and devices based on metal patterns can be widely used in many new and expanding industries,such as flat panel displays, alternative energy,sensors and so on. In this paper, we introduce a new transfer printing method for fabricating metal optics functional devices. This method can directly transfer a metal pattern from a polyethylene terephthalate (PET)supported UV or polydimethylsiloxane (PDMS) pattern to another PET substrate. Purely taking advantage of the anaerobic UV curing adhesive (a-UV) on PET substrate, metal film can be easily peeled off from micro/nano-structured surface. As a result, metal film on the protrusion can be selectively transferred onto the target substrate, to make it the metal functional surface. But which on the bottom can not be transferred. This method provides low cost fabrication of metal thin film devices by avoiding high cost lithography process. Compared with conventional approach, this method can get more smooth rough edges and has wider tolerance range for the original master mold. Future developments and potential applications of this metal transfer method will be addressed.
    • Realization of periodic InAs QDs by in-situ four-beam laser-interference irradiation on the wetting layer

      Yang, Linyun; Yang, Xinning; Miao, Lili; Zhang, Wei; Huo, Dayun; Shi, Zhenwu; Peng, Changsi; Soochow University; Suzhou Institute of Nano-Tech and Nano-Bionics; Jiangsu Entry-Exit Inspection and Quarantine Bureau; et al. (SPIE, 2018-12-31)
      In this paper, during InAs/GaAs (001) quantum dot molecular beam epitaxy growth, four-beam pulsed laser-interference was used to in-situ irradiate on the wetting layer with an InAs coverage of 1.1 monolayer. Significant atomic layer removal and periodic nanostructures including nanoholes and nanoislands were obtained. These periodic nanostructures had a significant influence on quantum dot growth. Especially for the structure of nano-island, quantum dots preferentially nucleated at the edges of them. When the nano-island size becomes small enough, ordered quantum dot arrays are directly achieved on smooth GaAs surface with a follow-up InAs deposition accompanied by the disappearance of the nanoislands. This finding provides a potential technique leading to site-controlled and defect-free quantum dot fabrication.
    • Study of in situ laser modification of Ga-droplets

      Yang, Xinning; Yang, Linyun; Miao, Lili; Zhuang, Siyi; Shi, Zhenwu; Peng, Changsi; Soochow University; University of Bedfordshire (SPIE, 2019-12-31)
      In this paper, we report the study on the size regulation of Ga-droplets by in situ laser irradiation. Gallium (Ga) droplets are grown on GaAs (001) substrate by molecular beam epitaxy (MBE) and the in situ laser irradiation is carried out by using an ultraviolet pulsed laser. The results show that: The laser irradiation will cause the expansion of Ga-droplets and then the adjacent Ga-droplets can touch with each other and larger Ga-droplets can be formed by the fusion of two or more droplets. So the size of Ga-droplets can be re-modified by laser irradiation and such modification is positively correlated with the irradiation intensity. In other words, we can easily define the size of Ga-droplets by using different laser irradiation energy.
    • Study of in situ laser modification of InAs/GaAs quantum dots

      Miao, Lili; Yang, Linyun; Yang, Xinning; Zhuang, Siyi; Shi, Zhenwu; Peng, Changsi; Soochow University; University of Bedfordshire (SPIE, 2019-12-31)
      We have investigated the modification of self-assembled InAs/GaAs quantum dots (QDs) by in situ pulsed laser irradiation. The QDs were fabricated by molecular beam epitaxy (MBE) in Stranski-Krastanov mode at 480℃ and then at the same temperature the pulsed laser was in situ introduced to modify the QDs with different energy. The dependence of morphology evolution on irradiation energy was carefully studied by AFM testing. The results show that laser excitation can enable both desorption and diffusion of In atoms which may induce strong modification on the InAs QDs. For irradiation of a moderate energy, the 3D dot-like InAs QD will transform into 2D oval-shaped island; Once the irradiation energy is high enough, the InAs QDs will be completely removed off from the surface. The involved mechanism is also discussed. Herein, we have proposed a new approach of fabricating QDs which is high-efficient, pollution-free, oxidation-free and defect-resistant and it is believed in the near future, it may find wide applications in both the fundamental physics research and emerging device manufacture.
    • Surface modification on GaAs by in-situ pulsed UV laser

      Guo, Xiaoxiang; Huo, Dayun; Zhang, Wei; Xu, Chao; Deng, Changwei; Peng, Changsi; Soochow University (SPIE, 2016-12-31)
      A single-beam of UV pulse laser (355nm/10ns) was used to irradiate the as-grown GaAs (100) surface in-situ in molecular beam epitaxy with pulse numbers from 1 to 6 at laser intensity of 52.5 mJ/cm2/pulse. It was observed that the irradiated GaAs surface morphology depended strongly on the pulse number. For single pulse irradiation, small nano-dots (NDs) with high density were produced on the surface. The size of NDs increased and nano-rings (NRs) were observed with the increasing of pulse numbers. The surface was completely dominated by NRs at 6 pulses of laser irradiating. Arsenic atoms were selectively desorbed away from GaAs surface by laser irradiation leaving plenty of naked Ga-atoms to form small metal-dots of Gallium. Ga-rich NDs transferred to Ga droplets with the increased number of the laser pulses. NRs formed just as the traditional droplet-epitaxy process when the droplet size grew up to a critical size. Nano-drill process played an important role in the process. This research was supposed to provide a novel and promising solution for more controllable nano-fabrication of various semiconductor materials of MBE growing, including but not limited to GaAs reported here.