2018 Fiscal Year Research-status Report
Multi-functional Al-catalyzed Si nanowires: self-assembled zero and one-dimensional hybrid nanostructure formations
| Project/Area Number |
18K14096
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
J. Wipakorn 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, 主任研究員 (40748216)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | Nanowire / Vapor-liquid-solid / Silicon / Aluminum |
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| Outline of Annual Research Achievements |
The multi-functional Al-catalyzed silicon nanowire (SiNW) growths on the controlling of shape transformation from smooth surface to nanodot (ND) and NW-surrounded structures were investigated. The effects of substrate temperature, SiNW growth time, Al catalyst thickness, SiH4 flow rate and growth chamber pressure on SiNW formation were studied. The optical and electrical properties of SiNWs for photovoltaic application were observed. Extremely low light reflectance below 10% and the Al doping concentration of less than 1019 cm-3 range were obtained in SiNW samples. The complete removal of Al catalyst was successfully done, and the Al-catalyzed SiNW-based solar cell fabrication was realized. The power conversion efficiency (PCE) could be enhanced upon 9 % with the optimization of SiNW length. Moreover, the Al-catalyzed SiNW formations and the solar cell fabrications on thin Si substrates provided by pre-chemical etch and post-mechanical polish methods have been extended to observe for suppressing the Si material consumption and to develop into the flexible devices. The PCE of thin SiNW solar cells were achieved at 5.0% by using post-polished Si substrates from 4.2% of pre-etched thin Si. These results attributed to the cell and junction leakages owing to thin Si substrate. All experimental results were presented in 3 conferences (1 international and 2 domestic conferences; poster presentations). The journal manuscripts are in progress.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
The studies on SiNW formations and device demonstrations were well progressed as explained in the research achievement part. But the order of research had been a little changed. SiNW positioning by array patterning of Al catalyst using nanoimprinting was slightly delayed due to the machine moving and reinstallation. Moreover, the present cost for purchasing a new nanoimprint quartz mold is over the budget. The mold already had some broken areas, affecting to the patterning yield of lithography process. However, the studies on Al-catalyst patterning using colloidal lithography, core-shell NW structures of Si/Ge heterojunction, B doping control in SiNWs using B2H6 gas, electrode fabrication and characterization of single NW for transistor application were alternately investigated during nanoimprint machine setting.
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| Strategy for Future Research Activity |
In this fiscal year, the studies on Al-catalyst patterning will be intensively progressed. The manuscripts of research results in the past fiscal year will be submitted for publication. The experimental results of core-shell NW structures of Si/Ge heterojunction, B doping control in SiNWs using B2H6 gas, electrode fabrication and characterization of single NW for transistor application will be presented and summarized. Some passivation techniques for NW interfacial defect reduction will be observed and more Al-catalyzed SiNW-based devices will be realized and developed.
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