第654回レーザー科学研究所コロキウム
●日時(Date):
2023.10.25 11:00-
○場所(Place):
レーザー科学研究所 研究棟3F 大会議室
ハイブリッド開催ですので、Zoomからでもご参加いただけます。
オンラインでの接続先：
https://us02web.zoom.us/j/84649212475
ミーティング ID: 846 4921 2475
●講演者(Speaker):
Zdenek Hubicka (Institute of Physics, Czech Academy of Sciences)
○題目(Title):
Reactive pulsed sputtering of semiconducting ternary oxide thin films
for photoelectrochemical applications
●概要(Abstract):
Reactive pulsed magnetron sputtering is recently intensively studied
as a tool for oxide semiconducting thin films depositions. One benefit
of this technology is good compatibility with industrial
processes. Great progress was done in different forms of reactive high
power impulse magnetron sputtering systems (r-HiPIMS) which were
already used for various types of oxide semiconducting thin films
depositions. This r-HiPIMS technique can provide high fraction of
sputtered particles to be ionized and relatively high ion fluxes with
specific energetic ion distribution function are detected in the
position of substrate. These parameters of r-HiPIMS plasma can
significantly influence semiconducting properties of deposited
films. The last options of HiPIMS technology includes positive pulse
allowing to boost and control of ion bombardment and ion fluxes on
growing films. Other options contain possibility to control current
and voltage waveforms in order to further influence plasma parameters
during the deposition process. We have used various forms of r-HiPIMS
techniques for the deposition of ternary oxide semiconducting thin
films which can work as thin film photoanodes or photocathodes in
photoelectrochemical cells which are suitable for solar water
splitting and hydrogen production. These ternary oxides were usually
deposited by r-HiPIMS co-sputtering from two metallic targets in Ar+O2
gas mixture. The first material which we have intensively studied were
CuFeO2 thin films with delafossite structure and p-type
conductivity. It was confirmed that r-HiPIMS technique can be used for
the deposition of CuFeO2 films with polycrystalline structure
containing delafossite phase under specific conditions in HiPIMS
plasma. These films were working as photocathodes in PEC cells and
photocurrents in cathodic regions were studied in specific
electrolytes. Electrochemical stability was assessed as well. Ternary
oxide films containing CuWO4 phase were deposited as n-type
semiconductor by r-HiPIMS co-sputtering in Ar+O2 gas mixture. Cu and W
metallic magnetron targets were used for this purpose. These films
were found functional as photoanodes for PEC cells and quite
pronounced photocurrents in anodic region were detected during
photoelectrochemical measurements. The electrochemical stability was
measured as well. In order to optimize deposition conditions for
these experiments, plasma parameters in r-HiPIMS systems were
investigated by ion mass spectrometry, time resolved emission
spectroscopy and time resolved Langmuir probe system. Furthermore a
new version of RF probe was developed which was able to measure ion
flux density, electron temperature and ion density with time
resolution. This new probe was very robust also in highly reactive
plasma and was able to work also in case the probe surface was coated
with electrically insulating layer. In this way, we were able to
monitor these plasma parameters also during all the time of deposition
process.
○連絡先(Contact Person):
山ノ井航平
