
332 Gallium Nitride (GaN): Physics, Devices, and Technology
gate bias, whereas interface states show a signicant change in their G
P
(ω)/ω spectra
when gate bias is changed [14,16,17].
The techniques described above (C-DLTS, DLOS, and g
m
-f) provide important
results on the properties of traps located under the gate of the devices; however,
due to the choice of the bias points (moderate drain bias), or to the layout of the
test structures used for the measurements (FAT-FETs and capacitors), they do not
provide exhaustive results on the trapping mechanisms that may occur in the gate-
drain access region. Moreover, these methods do not provide di