Organic vapor sensors based on functionalized macroporous Si using single and double-side electrochemical etching

Organic sensors for ethanol vapor detection were developed by means of electrochemical etching of crystalline silicon as initial substrate following two procedures: front side etching (FSE) and front- and backside (“double”) surface etching (DSE). The first consists on the attack of the crystalline...

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Bibliographic Details
Published in:	Microelectronic engineering Vol. 90; no. Feb; pp. 55 - 58
Main Authors:	Ramírez-Porras, A., Fahlman, B.D., Badilla, J.P., López, V.
Format:	Journal Article Conference Proceeding
Language:	English
Published:	Amsterdam Elsevier B.V 01-02-2012 Elsevier
Subjects:	Applied sciences Brazing. Soldering Cross-disciplinary physics: materials science; rheology Crystal structure Electrochemical etching Etching Ethanol Ethyl alcohol Exact sciences and technology Functionalization General equipment and techniques Instruments, apparatus, components and techniques common to several branches of physics and astronomy Joining, thermal cutting: metallurgical aspects Materials science Metals. Metallurgy Physics Porous materials; granular materials Porous silicon Sensors Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing Silicon Silicon substrates Specific materials Surface treatments Functionalization Porous silicon Sensors Ethanol Porous materials Measurement sensor Thickness Crystalline material Solder Integrated circuit bonding Back surface Pore size Chemical modification Response time Reproducibility Wafers Hydrofluoric acid Free-standing film Silicon Soldered joints Electrochemical etching
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Summary:	Organic sensors for ethanol vapor detection were developed by means of electrochemical etching of crystalline silicon as initial substrate following two procedures: front side etching (FSE) and front- and backside (“double”) surface etching (DSE). The first consists on the attack of the crystalline silicon surface by hydrofluoric acid (HF) in presence of a constant current flow to form a layer of vertically oriented pattern of pores with diameters in the 2–5μm range and a thickness of about 50μm. The second procedure is similar to the first one but allowing a similar etching to the opposite side of the silicon wafer. The etching times for both surfaces were adjusted in such a way to produce a free standing porous layer of around 300μm in thickness. The samples produced by FSE and DSE were submitted to a functionalization methodology using 4-aminopyridine to cover the porous surface. The obtained specimens were mounted in a holder with two soldered contacts and placed in a testing chamber where different flows of ethanol vapors were injected. Conductance responses of both kinds of sensors were recorded and compared between them and with respect to nontreated crystalline silicon samples in terms of sensing capability, reproducibility, and response times. The results indicate that both FSE and DSE sensors have improved sensing properties compared to the nontreated surfaces.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0167-9317 1873-5568
DOI:	10.1016/j.mee.2011.05.010