University of California, San Diego Main Page Sailor Group Home Department of Chemistry and Biochemistry, UCSD
Home Announcements Research People Publications Contact information

Porous Silicon Resources

 

What is porous silicon?

Porous silicon is a nanostructured material prepared by electrochemical or chemical etching of crystalline silicon. It was accidentally discovered by Uhlir at Bell Laboratories in the mid 1950s [1]. Quantum confinement effects and in particular room-temperature photoluminescence was discovered from this material in the late 1980s by two research groups working independently: Leigh Canham at the Defense Research Agency in England [2], and Ulrich Goesele and Voelker Lehmann at Duke University in the United States [3]. Both teams reasoned that the pore walls in the material could be made sufficiently thin to display quantum confinement effects. This intuition turned out to be correct, and the electrochemically etched material was reported to fluoresce with a bright red-orange color.[2] As expected from the quantum confinement relationship, this color is at an energy that is significantly larger than the bandgap energy for bulk Si, which occurs in the infrared region of the spectrum.
With the discovery of efficient visible light emission from porous Si came an explosion of work focused on creating Si-based optoelectronic switches, displays, and lasers. Problems with the material’s chemical and mechanical stability and its disappointingly low electroluminescence efficiency led to a waning of interest by the mid 1990s. In the same time period, the unique features of the material- its large surface area within a small volume, its controllable pore sizes, its convenient surface chemistry, and its compatibility with conventional silicon microfabrication technologies-inspired research into applications covering a vast range of disciplines-- electronics, biomedicine, optics, sensors, solar cells, and batteries.

<more>

1. Uhlir, A., Electrolytic shaping of germanium and silicon. Bell System Tech. J., 1956. 35: p. 333-347.
2. Canham, L.T., Si Quantum Wire Array Fabrication by Electrochemical and Chemical Dissolution. Appl. Phys. Lett., 1990. 57(10): p. 1046-1048.
3. Lehmann, V. and U. Gosele, Porous Silicon Formation: a Quantum Wire Effect. Appl. Phys. Lett., 1991. 58(8): p. 856-858.

 

Porous Si plan view image

Porous Si cross section


Etching video: how to make porous silicon

Instructional YouTube video "etching 101" on electrochemical preparation of porous silicon by etching crystalline silicon wafers in HF:ethanol solutions Includes tips on safety procedures and personal protective equipment. The procedure is focused on the preparations given in "Porous Silicon in Practice: Preparation, Characterization, and Applications." Wiley-VCH: Weinheim, Germany, 2012.

Standard etch cell
by Gha Young Lee

Upcoming Meetings

Porous Semiconductors Science and Technology (PSST) 2018
Run every two years since 1998, the PSST meeting is the premier meeting dedicated to porous semiconductors. The dates and location of the forthcoming 11th PSST Conference (PSST-2018) is not yet determined.

PSST Logo
2018 PSST

Summer School for Silicon Nanotechnology (SSSiN)

Run by Prof. Sailor since 2003, the Summer School for Silicon Nanotechnology (SSSiN) is an intensive, six week introduction to electrochemically nanostructured silicon. Based on the book "Porous Silicon in Practice" this hands-on course exposes participants to the preparation, characterization, and applications of porous silicon-based nanomaterials. Focused on research at the nano-bio interface, the program begins with an intensive training in theory, techniques and laboratory methods of silicon nanotechnology, and concludes with a capstone “Discovery Project”--an independent research project implemented by the student under the mentorship of a current research group member.

<more>

SSSiN students in lab 2014
2014 SSSiN participants: UCSD undergraduate mentor Rhiannon Kennard (center) with her team Lianfei Yan (left) and Tushar Kumeria (right).

Books on porous silicon

Canham, L. T. (ed), Handbook of Porous Silicon. Springer: Switzerland, 2014; 1017 pages. This is the bible for porous silicon researchers--a collection of chapters written by all of the leading experts in the field of porous silicon, comprehensively covering fabrication, properties, characterization, processing, and applications of porous silicon. Pretty much anything you might want to know about this material is in this book.

Sailor, M. J., Porous Silicon in Practice: Preparation, Characterization, and Applications. Wiley-VCH: Weinheim, Germany, 2012; 249 pages. How-to book written as a series of experiments that give step-by-step instructions in the preparation of the more common forms of porous silicon under study today: mesoporous films, macroporous films, microparticles, nanoparticles, photoluminescent porous silicon, photonic crystals, microcavities, and Bragg stacks. Available from Wiley-VCH or from Amazon.com

text


Software

For etching, characterizing, etc.

 

Researchers

Incomplete list of and links to key researchers working in the field of porous silicon.

Prof. Vivechana Agarwal, Autonomous State University of Morelos; MEXICO
Prof. Ekaterina Astrova, Ioffe Research Institute, Saint Petersburg; RUSSIA
Prof. Giuseppe Barillaro, Università di Pisa, ITALY
Prof. Brahim Bessais, Res.& Tech. Centre of Energy; TUNISIA
Prof. Luca Boarino, INRIM, Torino; ITALY
Prof. Leigh Canham, pSiMedica Ltd., UK
Prof. Andres Cantarero, University of Valencia, SPAIN
Prof. Jeffrey Coffer, Texas Christian University; USA
Prof. Frederique Cunin, CNRS; FRANCE
Prof. Luca De Stefano, IMM, Naples; ITALY
Prof. Thierry Djenizian, Universités d'Aix-Marseille; FRANCE
Prof. Gael Gautier, University of Tours; FRANCE
Prof. Justin Gooding, University of New South Wales, Sydney; AUSTRALIA
Mag. Dr. Petra Granitzer, University of Graz; AUSTRIA
Prof. Adrian Keating, University of Western Australia, Crawley; AUSTRALIA
Prof. Roberto Koropecki, INTEC-UNL-CONICET, Santa Fe; ARGENTINA
Prof. Nobuyoshi Koshida, Tokyo University of A&T, JAPAN
Prof. Enrique Quiroga, Benemerita Universidad Autonoma de Puebla (BUAP); MEXICO
Prof. Klemens Rumpf, University of Graz; AUSTRIA
Prof. Amir Saar, The Hebrew University of Jerusalem; ISRAEL
Prof. Michael Sailor, University of California, San Diego, USA
Prof. Jarno Salonen, Turku University; FINLAND
Prof. Patrik Schmuki, Univerity of Erlangen; GERMANY
Prof. Ester Segal, Technion; ISRAEL
Prof. Honglae Sohn, Chosun University; KOREA
Prof. Victor Timoshenko, Lomonosov Moscow State University, RUSSIA
Prof. Nico Voelcker, Mawson Institute, University of South Australia; AUSTRALIA
Prof. Sharon Weiss; Vanderbilt University, Nashville, USA
Prof. Jianmin Wu, Zhejiang University; CHINA

 

Companies working in the porous silicon field

Incomplete list of the companies who make or use porous silicon.

Advanced Micromachining Tools (AMMT)
Porous silicon etching equipment

Beijing ITEC Technologies Co., Ltd

Oncosil Medical
Treatment of pancreatic and liver cancer via radiotherapeutics embedded in porous Si

PicoTechnologies Nano Materials Co, Ltd.
Sensors for explosives and industrial pollutants

Porous Silicon.com
Porous silicon, etching equipment, specialized services

pSiVida
Medical therapeutics

Silicium Energy
Thermoelectrics

Silicon Kinetics
Biosensors

SiLiMiXT
Porous silicon materials, specialized services

Spinnaker Biosciences
Medical therapeutics

TruTag Technologies
Taggants for anti-counterfeiting applications

 

   

 


Related links

 
http://ab-initio.mit.edu/photons/tutorial More than you ever wanted to know about the quantum physics of photonic crystals
www.zyvex.com/nanotech/feynman.html The talk that started it all: Richard Feynman's 1959 "There's plenty of room at the bottom" lecture
http://learn.watch/the-three-laws-of-nanorobotics-michael-sailor-tedxucsd/ Prof. Sailor's TEDx Talk on Nanotechnology: "The Three Laws of Nanorobotics"

This page and its content copyright (c) Michael J. Sailor, 2015. Project funding supplied in part by the National Science Foundation (DMR-1210417). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.