The gallium nitride nanowires grown by NIST Physical Measurement Laboratory scientists measure only a few tenths of a micrometer in diameter, but they promise a very wide range of applications, from new light-emitting diodes and diode lasers to ultra-small resonators, chemical sensors, and highly sensitive atomic probe tips. The metal probe is used to examine proximity effects on the lasing properties of the nanowire.
GaN emits light when holes and electrons recombine at a junction created by doping the crystal to create p-type and n-type regions. These layers are formed by a variety of deposition methods, typically on a sapphire or silicon carbide substrate. Conventional methods produce crystals with relatively high defect densities. Unfortunately, defects in the lattice limit light emission, introduce signal noise, and lead to early device failure.
The Boulder team, by contrast, grows virtually defect-free hexagonal GaN nanowires very slowly from a silicon base. The combination of high mechanical quality factor and tiny mass also makes them capable of detecting masses in the sub-attogram range.
Also: Learn about GaN high-power electronics.
