Monday, September 26, 2005

"CHIPS: Semiconductors from algae? It's no fish tale"

Using chemical deposition and other techniques, Georgia Institute of Technology researchers have demonstrated that microscopic algae — silicon-dioxide diatoms — can be converted into semiconductors without changing the intricate structure of the organism's shell. The ability to mass-produce the shellfish easily and form thin films of them in uniform arrays prompted the researchers to convert them into semiconductors. Nearly 20 percent of living things are 10-micron-diameter unicellular algae called diatoms — microscopic silicon-dioxide shellfish that float in every sea, lake, river and stream. Diatoms, which eat carbon dioxide and give off oxygen, generate 40 percent of the 50 billion tons of organic carbon in the sea. They multiply by doubling, enabling enormous populations to grow quickly. By doubling their number every generation, diatoms can be grown in almost any amount necessary — 40 reproduction cycles yield 1 trillion replicas. Sandhage's method first evicts the tenants, leaving only the intricately patterned silicon-dioxide shell with thousands of compartments inside, measured in nanometers. Ideally, the internal structure would be programmed by genetic engineering so that each 10-micron diatom shell would be about as smart as a microprocessor.