K. Toya

Dynamics of debris from laser-irradiated Sn droplet for EUV lithography light source

In the development of extreme ultraviolet (EUV) light source at 13.5 nm for EUV lithography system by laser-produced plasma (LPP), a Tin (Sn) micro-droplet target is considered as a one of the promising targets for debris mitigation. In addition, double pulse irradiation scheme is regarded to be effective in order to improve the conversion efficiency to EUV light in the use of the droplet target. In our study, the dynamics of debris from the Sn droplet target irradiated by double pulses was investigated in order to establish the guideline for the optimum design of the mitigation system. The kinetic behaviors of the Sn atoms and of the dense particles from Sn droplet target irradiated by double pulses from the Nd:YAG laser and the CO2 laser were investigated by the laser-induced fluorescence imaging method and a high-speed imaging, respectively. After the pre-pulse irradiation of the Nd:YAG laser, the Sn atoms were ejected in all direction from the target with a speed of as fast as 20 km/s and the dense particle cloud expanded by a reaction force due to the plasma expansion with a speed of approximately 500 m/s. The expanding target was subsequently irradiated by the main-pulse of CO2 laser and the dense cloud was almost disappeared by main-pulse irradiation.

Synthesis of layer-structured ZnO nano-crystals by nanoparticle-assisted pulsed laser deposition

Zinc oxide (ZnO) nanowires have attracted a great attention for next optoelectronic applications, such as an UV-LED. We have been succeeded in growing vertically-aligned ZnO nanowires by nanoparticle-assisted pulsed-laser deposition (NAPLD) without using any catalyst. In this study, we fabricated layer-structured ZnO nanowires by NAPLD using a multi-target changer system.

Fabrication of layer structured ZnO nanowire by nanoparticle-assisted pulsed laser deposition for optoelectronic application

ZnO nanowires have attracted a great attention as building blocks for the optoelectronic devices. For the practical optoelectronic applications based on the ZnO nanowires, a synthesis technique for layered structure has significant advantage to fabricate a pn junction, a core/shell structure, and a multiple quantum well structure. We have been succeeded in growing nanowires on the pre-deposited ZnO film and core/shell structure by a newly developed nanoparticle-assisted pulsed-laser deposition (NAPLD) using multi-target changer. In this paper, recent progresses of synthesis of layer-structured ZnO nanowires by the NAPLD are described.

Synthesis and characterization of layer structured ZnO nanowire for ultraviolet light-emitting diode

We have been succeeded in growing vertically aligned ZnO nanowires by a newly developed nanoparticle-assisted pulsed-laser deposition (NAPLD) without any catalyst. In this study, layer structured ZnO nanowires, such as film-wire layered structure and core/shell structure, were synthesized using multi-target changer system. In this paper, synthesis and photoluminescence characteristic of the layer structured ZnO nanowires are described.

Synthesis of ZnO nanowire with dope of phosphorus by NAPLD and its characteristic evaluation

Phosphorus doped ZnO (ZnO:P) nanowires have been successfully grown on the annealed c-cut sapphire substrate using catalyst-free nanoparticle-assisted pulsed-laser deposition, and characteristics of the nanowires was evaluated. A sintered ZnO target doped with P2 O5 was used for synthesis the ZnO:P nanowires.

Patterned growth of ZnO nanowires using NAPLD with nano-imprint

For the practical optoelectronic applications based on the ZnO nanowires, control the growth position of ZnO nanowires is essentially required. In this paper, we describe progress of synthesis the patterned growth of ZnO nanowires by chemical vapor deposition method and nanoparticle assisted pulsed laser deposition method using nano-imprinting technique.

Synthesis and characterization of ZnO nanocrystals by nanoparticle-assisted pulsed laser deposition

ZnO nano-crystals have been paid a great attention as building blocks for the optoelectronic devices. We have been succeeded in growing ZnO nanostructures, such as vertically-aligned ZnO nanowires and nanowalls, by a newly developed nanoparticle-assisted pulsed-laser deposition (NAPLD) without using any catalyst. Depending on the growth condition a film-wire heterostructured ZnO were synthesized on the c-plane sapphire substrates. The room temperature photoluminescence spectrum of synthesized ZnO nanostructures exhibited a strong intrinsic UV emission and a week defect-related visible emission.

Diagnostics of ablation dynamics of tin micro-droplet for EUV lithography light source

The ablation dynamics of tin micro-droplet target irradiated by double pulses was investigated for extreme ultraviolet lithography source. Debris from Sn droplet target was visualized by the laser-induced fluorescence imaging and shadowgraph imaging.