Fabrication of regular silicon microstructures by photo‐electrochemical etching of silicon

Abstract

PACS 81.05. Cy, 82.45.Qr, 82.45.Vp In this paper photo-electrochemical etching of silicon in HF-based solutions is employed as a versatile technique for fabrication of original silicon microstructures, alternative to commonly used methods. Photo-electrochemical etching, a well known technique for regular macropore formation, has been exploited to produce a multitude of different regular silicon microstructures (microtubes, microtips, microchannels, microspirals, micropillars, microwalls, etc.). This micromachining technique is here detailed and some applications are reported.

Long Germanium Nanowires Prepared by Electrochemical Etching

“…The preparation technique for Ge nanowires presented is a rather slow process, because the etching conditions (temperature, electrolyte concentration, doping level) must allow for the formation of deep pores in Ge; but in comparison to the other techniques for the formation of nanowires, electrochemical etching is easy and cheap. Under special etching conditions, similar nanowires have been etched in Si as well. , Our results for Ge allow a more general interpretation of the experimental results and thus may help to understand fully the nanowire growth mechanism. Because the arrangement of the pores is an essential parameter for the formation, lithography could be used for prestructuring the pore nucleation sites, allowing for optimized nanowire formation conditions.…”

“…One-dimensional nanostructures, such as nanotubes, nanowires, nanorods, and nanobelts, are receiving increasing attention because finite size effects result in various unusual properties enabling novel electronic, optical, and mechanical nanodevices. − Nanowires of different compositions have been prepared by a variety of methods including laser ablation, template-assisted electrochemistry, , chemical transportation, chemical vapor deposition , and solvothermal methods, and semiconductor-based nanostructures are of increasing interest. Although there are many reports considering silicon nanowires, − only a few publications concerning the preparation of germanium nanowires existed until now. ,,, However, Ge nanowires hold some special interest in comparison to other semiconductors because Ge has, for example, a higher electron and hole mobility than silicon, which would be advantageous for high-performance transistors with nanoscale gate lengths. − …”

Metal electrode integration on macroporous silicon: pore distribution and morphology

“…Macroporous silicon has been demonstrated as an interesting material for a number of applications such as silicon micromachining [1,2], photonic [3], and sensing [4,5]. The integration of metal electrodes on macroporous silicon surface is of paramount importance in case of sensing applications [6].…”

Macroporous Semiconductors

“…There is also no lack of reviews. In [13,14,15,16,17,18,19,20,21,22] many aspects of pores in semiconductors are highlighted; more recent reviews deal with macropores in Si [23], self-organization issues in the context of pore formation in semiconductors [24], the luminescence from porous Si [18,25,26,27], or the use of impedance techniques for in situ assessment of pore growth [28]. …”