High Resolution Imaging of Electrical Properties of a 2-Inch-Diameter Gallium Nitride Wafer Using Frequency-Agile Terahertz Waves

摘要

The reflective spectra of n-type gallium nitride (GaN) samples with various carrier concentrations have been measured in the terahertz region. We observed the different reflective spectra by changing the carrier concentration. The Drude Lorentz model explained well the measured spectra influenced by free carrier effects. In order to obtain electrical properties of the carrier concentration, mobility, and electrical resistivity, we used two terahertz waves generated by a frequency-agile source. Image mapping of these electrical properties on a 2-in.-diameter GaN wafer was demonstrated with a high resolution of 1 × 1 mm~2.