NIST Researchers Develop Method for Producing GaN Nanowires
Source/Type: News - Staff reports

Author: CompoundSemi News Staff

July 26, 2010... Researchers at the National Institute of Standards and Technology have been able to grow thousands of evenly spaced nanowires on silicon in a formation that looks like a pin screen. The researchers detailed their experiments in Advanced Functional Materials. The gallium nitride nanowires were relatively defect free and pure. The researchers claim to have controlled the diameter and placement of the nanowires better than others have reported about catalyst-based nanowires. Such nanowires have applications in sensors and lasers. The researchers reportedly grew the nanowires layer by layer on silicon using molecular beam epitaxy.

The key trick in the growth was first creating a stencil like mask with precisely defined holes through which the nanowires could be grown. According to the researchers, mask openings ranged from 300 to 1000 nanometers (nm) wide, in increments of 100 nm. A single nanowire grew, with a well-formed hexagonal shape and a symmetrical tip with six facets grew in each opening of 300 nm or 400 nm. Larger openings produced more variable results. Openings of 400 nm to 900 nm yielded single-crystal nanowires with multifaceted tops. Structures grown in 1,000-nm openings appeared to be multiple wires stuck together. All nanowires grew to about 1,000 nm tall over three days.

Lead researcher Kris Bertness says that although the growth temperatures are too high (over 800 degrees Celsius) for silicon circuitry to tolerate, there may be ways to grow the nanowires first and then protect them during circuitry fabrication.

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