NIST researchers have developed advanced metrology techniques using gallium nitride (GaN) nanowires for semiconductor characterization and device fabrication. Key developments include:
1. GaN nanowire LEDs: Arrays of nanowire LEDs with controlled location and spatial layout have been fabricated using selective epitaxy methods. These LEDs have been combined to create on-chip optical interconnects.
2. Scanning probe metrology: GaN nanowires are being developed as multifunctional scanning probe tips combining light emission, microwave reflection, and topology measurement. They are more durable and reproducible than traditional NSOM and NSMM tips.
3. Optical measurements: Time-resolved photoluminescence and geometrical variations in nanowires have been used to extract surface recombination velocity and measure internal quantum efficiency without relying on low-temperature assumptions.
4. Doping measurements: Multiple methods have been pursued to extract carrier concentration in GaN nanostructures, including Raman spectroscopy, terahertz absorption, electrical resistance measurements, and scanning probe techniques.
5. High Q nanoscale mechanical resonators: GaN nanowires have demonstrated unusually low mechanical resonance losses, with potential applications in mass and temperature sensing.
6. FETs and sensors: Nanowire MESFETs and MOSFETs with low subthreshold swing have been fabricated and tested, showing high switching efficiency. GaN nanowires have also proven effective as chemical sensing devices and liquid crystal probes.
The research team is collaborating with institutions including the University of Colorado Boulder, University of Colorado Colorado Springs, Paul Drude Institut (Berlin), and University of Notre Dame. GaN nanostructure arrays with calibrated reference dimensions are available as Standard Reference Instrument 6012.
Source: https://www.nist.gov/programs-projects/gan-nanowire-metrology-and-applications
Keywords: GaN, nanowires, Raman spectroscopy, photoluminescence, x-ray diffraction, LEDs, metrology, scanning probe metrology, optical measurements, doping measurements, high Q nanoscale mechanical resonators, FETs, sensors, Standard Reference Instrument 6012
