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Arita, Ren*; Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Empizo, M.*; Hori, Tatsuhiro*; Fukuda, Kazuhito*; Minami, Yuki*; Sarukura, Nobuhiko*; Maruyama, Momoko; et al.
Optical Materials, 36(12), p.2012 - 2015, 2014/10
Times Cited Count：9 Percentile：45.71(Materials Science, Multidisciplinary)A single shot image of a ZnO crystal excited by the EUV laser of Kansai Photon Science Institute was captured. The evaluated EUV beam waist radii from the ZnO emission pattern along the horizontal and vertical axes are 5.0 and 4.7
m, respectively. The expected focal spot size of EUV laser and the spatial resolution of the magnifier (including the Schwarzschild objectives and lenses) are however 1 and 4m, respectively. The discrepancy on the spatial resolutions is attributed to exciton diffusion. We estimated the ZnO exciton diffusion length from the effective decay time which is shortened by exciton-exciton collision quenching and which is dependence on excitation energy density. Our results indicate that the short lifetime of ZnO is required to improve the spatial resolution.
imaging device of high spatial resolution ZnO scintillatorNakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Takeda, Kohei*; Nishi, Ryosuke*; Minami, Yuki*; Cadatal-Raduban, M.*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; et al.
Japanese Journal of Applied Physics, 50(12), p.122202_1 - 122202_4, 2011/12
Times Cited Count：9 Percentile：38.03(Physics, Applied)We demonstrate the potential of a hydrothermal method-grown ZnO as a high-spatial resolution imaging device for in-situ soft X-ray laser diagnostics by characterizing the exciton emission patterns. By plotting the emission pattern radii at each position, we estimated the evolution of the beam radius around the focal point. The beam profile of the Ni-like Ag ion plasma laser was estimated from the waist radii as 29 and 21m, the divergence angle as 7.2 and 11 mrad and the M2 factor as 47 and 50 in the horizontal- and vertical-axis, respectively. Spatial resolution of the magnifier was estimated to be 6m and is expected to improve by optimizing the optics of the magnifier and using a telescope. Our results would enhance the use of ZnO as an imaging device that would play a crucial role in the development and application of soft X-ray light sources.
Kawachi, Tetsuya; Hasegawa, Noboru; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Oba, Toshiyuki; Kaihori, Takeshi; Kishimoto, Maki; Ochi, Yoshihiro; Tanaka, Momoko; et al.
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.15 - 24, 2011/12
This paper reviews recent improvement in the source development of laser-driven X-ray lasers and the applications in the research fields of material science, laser processing, X-ray imaging, and radiation damage in biological cells. In the application for material science, we have firstly observed temporal correlation between the domain structures of ferro-electric substance under the Curie temperature. In the laser processing, new X-ray laser interferometer reveals us the nano-scale surface distortion of substance pumped by a femto-second optical pulse. In the X-ray diffraction image, we have taken several static images of micro-structure of samples: now we are trying to extend the objective to nano-scale dynamics using pump and probe method. In the radiation damage of biological cells, we observed double strand break in DNA using X-ray laser exposure; this results are compared with the case using incoherent several KeV X-ray exposure.
Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Terakawa, Kota*; Tomita, Takuro*; Yamamoto, Minoru; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Imazono, Takashi; et al.
X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.353 - 358, 2011/12
The understanding of the dynamics of the initial process is important for the micro processing and welding by the ultra-short laser pulse. The X-ray laser is suitable for probing this initial process because it has short wavelength (Ni-like Ag, 13.9 nm) and short duration (7 ps). For this investigation, the origin of time of the pumping pulse is quite important. In this study, we used the scintillation plate and the plasma gate technique to realize the spatial and temporal synchronization of the pump and probe pulses. For the spatial alignment, a CsI scintillation plate that was set at the sample position was illuminated by both the X-ray laser pulse, and the fluorescence light were detected by the CCD camera. For the temporal synchronization, we set a thin foil at the sample position. We measured the transmission of the X-ray laser while changing a temporal delay of the pumping laser with respect to the time of X-ray laser pulse to obtain the origin of the irradiation time.
Tanaka, Momoko; Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Oba, Toshiyuki; Kaihori, Takeshi; Ochi, Yoshihiro; et al.
JAEA-Conf 2011-001, p.126 - 128, 2011/03
The spatial resolution of hydrothermal method grown zinc oxide (ZnO) scintillator was evaluated using X-ray laser focused with Fresnel zone plate. The fluorescence image of the ZnO scintillator was measured to be less than 10um using CCD camera coupled with a Schbartzchild expander mirror. The availability of large size ZnO crystal up to 3-inch is quite attractive for future lithography and imaging applications.
Sarukura, Nobuhiko*; Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Ehrentraut, D.*; Fukuda, Tsuguo*; Tanaka, Momoko; Nishikino, Masaharu; Kawachi, Tetsuya
Reza Kenkyu, 39(3), p.193 - 196, 2011/03
Development of light sources in the soft X-ray/X-ray region, such as laser induced plasma emission and XFEL, is in demand for applications in various fields of science, medicine, and industry, among others. To promote this endeavor, development of imaging devices as diagnostic tools in this wavelength region is required. ZnO is a prominent candidate material for high spatial and temporal resolution imaging devices because of its emission at 380 nm, lifetime of less than 1 ns, and availability of large and cheap but high quality crystals. We obtained a single shot image of ZnO emission pattern excited by an X-ray laser at the Advanced Photon Research Center, Japan Atomic Energy Agency. The spatial resolution was estimated to be around 10 m. This result shows that ZnO can be used as a powerful imaging device for applications such as EUV lithography.
Nakazato, Tomoharu*; Furukawa, Yusuke*; Tanaka, Momoko; Tatsumi, Toshihiro*; Nishikino, Masaharu; Yamatani, Hiroshi*; Nagashima, Keisuke; Kimura, Toyoaki*; Murakami, Hidetoshi*; Saito, Shigeki*; et al.
Journal of Crystal Growth, 311(3), p.875 - 877, 2009/01
Times Cited Count：24 Percentile：86.17(Crystallography)The temperature dependence of scintillation properties of a hydrothermal-method-grown zinc oxide (ZnO) emission is investigated using a nickel-like silver laser emitting at 13.9 nm. A broad peak at 386 nm with a full-width at half-maximum (FWHM) of 15 nm at room temperature (298 K) is obtained. The peak position tends to be blue shifted while the FWHM becomes narrower when the crystal temperature is decreased to 25 K. Streak images fitted by a double exponential decay reveal that the measured emission decay at 105 K was 
= 0.88 ns and 
= 2.7 ns. This decay time of a few nanoseconds is suitable for lithographic applications and is sufficiently short for the characterization of laser plasma extreme ultraviolet (EUV) sources with nanosecond durations.
Tanaka, Momoko; Furukawa, Yusuke*; Nakazato, Tomoharu*; Tatsumi, Toshihiro*; Murakami, Hidetoshi*; Shimizu, Toshihiko*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Kawachi, Tetsuya; Kagamitani, Yuji*; et al.
X-Ray Lasers 2008; Springer Proceedings in Physics, Vol.130, p.501 - 505, 2009/00
We measured the time-resolved fluorescence spectra of ZnO and GaN single crystals excited by an X-ray laser operating at 13.9 nm and evaluated their scintillation properties for EUV excitation as compared with UV excitation case. For ZnO, a clear fluorescence peak of excitonic origin was observed at around 380 nm and the decay lifetime of less than 3 ns is found to be almost similar to the UV excitation case. The fluorescence at 380 nm is ideal for scintillator device design in the EUV and further applications. For GaN, the lifetimes are much longer than ZnO and the temporal profile of the EUV-excited fluorescence differs with the UV excitation case. As such, the EUV scintillation properties of ZnO is said to be more favorable than GaN. Finally, it is also demonstrated that an X-ray laser is an excellent tool for spectroscopic characterization of materials intended for next-generation lithography applications.
Furukawa, Yusuke*; Tanaka, Momoko; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nishimura, Hiroaki*; Mima, Kunioki*; Kagamitani, Yuji*; et al.
Reza Kenkyu, 36(APLS), p.1028 - 1030, 2008/12
Optical technologies in extreme ultraviolet (EUV) region have been receiving strong interests for the next generation lithography. Here we report properties of ZnO as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The ZnO sample was irradiated with EUV laser pulses and the fluorescence was measured using a streak camera fitted with a spectrograph. A clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. The prominent peak fluorescence is ideal for EUV detection and further applications including imaging.
Furukawa, Yusuke*; Tanaka, Momoko; Nakazato, Tomoharu*; Tatsumi, Toshihiro*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kimura, Toyoaki; Murakami, Hidetoshi*; Saito, Shigeki*; et al.
Journal of the Optical Society of America B, 25(7), p.B118 - B121, 2008/07
Times Cited Count：24 Percentile：72.65(Optics)Using EUV laser operated at 13.9 nm ZnO and GaN are shown to be excellent scintillators in this wavelength region. Especially ZnO has short response time of 3 ns and prominent peak fluorescence from excitation at 380 nm.
Tanaka, Momoko; Furukawa, Yusuke*; Sarukura, Nobuhiko*
Purazuma, Kaku Yugo Gakkai-Shi, 84(7), p.443 - 445, 2008/07
X-ray laser is a characteristic EUV source with short pulse duration of several pico-seconds, narrow spectral width, and high coherence. As an application of the X-ray laser, the UV emission from the ZnO single crystal excited by the 13.9 nm X-ray laser was observed and evaluated for EUV scintillator. The response time is sufficiently short for characterizing EUV lithography light sources having several nanoseconds duration. It is also shown that the X-ray laser is an excellent tool for time-resolved spectroscopy and characterization of materials intended for next-generation lithography applications.
Tanaka, Momoko; Furukawa, Hiroyuki*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kagamitani, Yuji*; Ehrentraut, D.*; et al.
Journal of Physics; Conference Series, 112(4), p.042058_1 - 042058_4, 2008/00
Times Cited Count：1 Percentile：55.21(Physics, Fluids & Plasmas)Optical technologies in the extreme ultraviolet (EUV) region have been receiving strong interest for the next generation lithography. Efficient and fast scintillators are one of the key devices functioning in the EUV region. In this paper, we report excellent properties of ZnO and GaN as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The sample was irradiated with EUV laser pulses, and the fluorescence spectrum and the fluorescence lifetime were measured using a streak camera fitted with a spectrograph. In the case of ZnO, a clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. For GaN, a fluorescence peak at 370 nm having slower 5-ns decay time was observed. In this respect, the EUV scintillation properties of ZnO is said to be more favorable than GaN.
Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kimura, Toyoaki; Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; et al.
Applied Physics Letters, 91(23), p.231117_1 - 231117_3, 2007/12
Times Cited Count：52 Percentile：84.56(Physics, Applied)The scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal are evaluated for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength. The exciton emission lifetime at around 380 nm is determined to be 1.1 ns, almost identical to ultraviolet laser excitation cases. This fast response time is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. The availability of large size ZnO crystal up to 3-inch is quite attractive for future lithography and imaging applications.
Furukawa, Yusuke*; Murakami, Hidetoshi*; Sarukura, Nobuhiko*; Tanaka, Momoko; Nishikino, Masaharu; Nagashima, Keisuke; Kimura, Toyoaki; Yamatani, Hiroshi; Yoshikawa, Akira*; Fukuda, Tsuguo*
no journal, ,
Using Ni-like Ag extreme ultraviolet (EUV) laser operated at 13.9-nm, ZnO is shown to be the excellent scintillator in this wavelength region with sufficiently short response time of less than 3 nsec and prominent peak fluorescence originated form exciton at 380 nm.
Tanaka, Momoko; Furukawa, Yusuke*; Murakami, Hidetoshi*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Nagashima, Keisuke; Kimura, Toyoaki; Yamatani, Hiroshi; Yoshikawa, Akira*; Fukuda, Tsuguo*
no journal, ,
Using Ni-like Ag extreme ultraviolet (EUV) laser operated at 13.9-nm, ZnO is shown to be the excellent scintillator in this wavelength region with sufficiently short response time of less than 3 nsec and prominent peak fluorescence originated form exciton at 380 nm.
Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; et al.
no journal, ,
Zinc oxide (ZnO) has previously been reported to be a potential light-emitting diode materia. We measured the time-resolved emission spectrum of a ZnO crystal for extreme ultraviolet (EUV) laser excitation at 13.9 nm wavelength and compared with UV excitation case. The emission lifetime was determined to be 2.6 ns. This value was not changed even for ultraviolet laser excitation. In the context of the nanosecond regime in the EUV region, ZnO crystal promises to be a feasible scintillation material.
Sarukura, Nobuhiko*; Furukawa, Yusuke*; Murakami, Hidetoshi*; Saito, Shigeki*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; et al.
no journal, ,
Optical technologies in the extreme ultraviolet (EUV) region have been receiving strong interest for the next generation lithography. Here we report properties of ZnO and GaN as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The sample was irradiated with EUV laser pulses and the fluorescence were measured using a streak camera fitted with a spectrograph. In the case of ZnO, a clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns, as shown in Fig. 1. The prominent peak fluorescence is ideal for EUV detection and further applications including imaging. For GaN, a fluorescence peak at 370 nm having slower 5-ns decay time was observed. In this respect, the EUV scintillation properties of ZnO is said to be more favorable than GaN.
Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Takatori, Satoru*; Estacio, E.*; Cadatal, M.*; Sarukura, Nobuhiko*; Nishimura, Hiroaki*; Mima, Kunioki*; Tanaka, Momoko; et al.
no journal, ,
We have observed the single shot, focused image of a EUV laser through the emission of a ZnO scintillator. An estimated EUV laser focal spot size of 50
88 micrometer is reasonable considering the long focal length of the spherical mirror. This work reports a feasible method to perform single-shot beam diagnostics for EUV laser sources using a ZnO crystal scintillator. Furthermore, since the ZnO fluorescence is at 380 nm wavelength, the imaging optics for the diagnostics can all be placed outside the vacuum chamber; thereby making experiments less cumbersome. Having a capability in fast and efficient beam profiling of EUV laser sources with acceptable resolving power is very important in future lithography applications.
Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Sakai, Kohei*; Sarukura, Nobuhiko*; Ehrentraut, D.*; Fukuda, Tsuguo*; Tanaka, Momoko; Nishikino, Masaharu; Yamatani, Hiroshi*; et al.
no journal, ,
no abstracts in English
Nishikino, Masaharu; Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Ishino, Masahiko; Imazono, Takashi; Tanaka, Momoko; Sato, Katsutoshi; Yamamoto, Minoru; Oba, Toshiyuki; et al.
no journal, ,
Recent Progress in the development of laser-driven plasma soft X-ray laser (XRL) and the applications are presented. In the source development, TOPAZ laser using Nd:glass zigzag slab amplifiers with 10 J, 0.1 Hz repetition-rate routinely provides the fully spatial coherent X-ray laser at 13.9 nm for the applications. The bright, coherent, and picoseconds X-ray pulse can be used in a variety of applications such as X-ray speckle measurement and interferometer for probing materials, diffraction imaging, nano-scale fabrication, radiation biology, and so on. In order to extend the use of XRLs, now we are constructing new XRL beam lines for the optical pump and XRL probe experiment.
