Functional Applications of Nanostructured Silicon
Prof. Nobuyoshi Koshida
Graduate School of Engineering, Tokyo University of Agri. & Tech., Koganei, Tokyo 184-8588, Japan
http://www.tuat.ac.jp/~koslab/
17:00 - 18:00 Tuesday 31 May 2016 KFU HS 5.01 Along with the continuing activity of seeking further scaling merits, the heterogeneous integration becomes important in advanced silicon device technology toward the development of higher-value devices. As being a material with versatile properties, nanostructured silicon can be platform for functional combinations. Topics of studies on its photonic, electronic, structural, and acoustic applications are discussed here.
Visible luminescence appeared in quantum-sized nano-Si is linked with the photoconductive or photovoltaic effect in the short wavelength region corresponding to a widened band gap. Observed intrinsic electroluminescence and avalanche photoconduction suggest that the hot electron effect is enhanced in nano-Si dots. Related phenomenon is ballistic hot electron emission from a nano-Si diode. In vacuum, mask-less multi-beam lithography has been developed by employing the active-matrix drive [1]. This emitter operates even in atmospheric-pressure gases and solutions. In the latter case, the reducing activity of hot electrons leads to thin film deposition of metals, Si, Ge, and SiGe [2]. Thin Cu film deposition has been confirmed under a printing mode as well, in which emitted electrons impinge on target substrates coated with Cu-salt solutions [3]. An extremely big difference in the thermal effusivity between nano-Si and crystalline silicon makes it possible to operate the nano-Si device as an efficient thermo-acoustic emitter. Owing to the broad-band emissivity in the audible to ultrasound region with no harmonic distortions, the emitter is useful for generating sound under a full digital drive [4] and reproducing complicated ultrasonic communication calls between mice [5]. Pore-filling by magnetic materials [6] and hetero-epitaxial growth indicate another usefulness of nano-Si structure as a template.
This work was partially supported by JSPS and NEDO, Japan.
References
1. M. Esashi, A. Kojima, N. Ikegami, H. Miyaguchi, and N. Koshida, Microsystems & Nanoeng. 1, 15029 (2015).
2. N. Koshida, A. Kojima, T. Ohta, R. Mentek, B. Gelloz, N. Mori, and J. Shirakashi, ECS Solid State Lett. 3(5), P57 (2014).
3. R. Suda, M. Yagi, A. Kojima, N. Mori, J. Shirakashi, and N. Koshida, J. Electrochem. Soc. 163(6), E162 (2016).
4. N. Koshida, D. Hippo, M. Mori, H. Yanazawa, H. Shinoda, and T. Shimada, Appl. Phys. Lett. 102, 123504 (2013).
5. A. Asaba, S. Okabe, M. Nagasawa, M. Kato, N. Koshida, K. Mogi, and T. Kikusui, PLoS One 9(2), e87186 (2014); .J. Vis. Exp.
103, e53074 (2015).
6. K. Rumpf, P. Granitzer, N. Koshida, P. Poelt, and H. Michor, ECS J. of Solid State Sci. Tech. 4(5), N41 (2015).
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