摘要：The characteristics of traps between the Al
0.25Ga
0.75N barrier and the GaN channel layer in a high-electron-mobility-transistors (HEMTs) were investigated. The interface traps at the Al
0.25Ga
0.75N/GaN interface as well as the border traps were experimentally analyzed because the Al
0.25Ga
0.75N barrier layer functions as a dielectric owing to its high dielectric constant. The interface trap density
D
it
and border trap density
N
bt
were extracted from a long-channel field-effect transistor (FET), conventionally known as a FATFET structure, via frequency-dependent capacitance–voltage (C–V) and conductance–voltage (G–V) measurements. The minimum
D
it
value extracted by the conventional conductance method was 2.5 × 10
12 cm
−2·eV
−1, which agreed well with the actual transistor subthreshold swing of around 142 mV·dec
−1. The border trap density
N
bt
was also extracted from the frequency-dependent C–V characteristics using the distributed circuit model, and the extracted value was 1.5 × 10
19 cm
−3·eV
−1. Low-frequency (1/
f) noise measurement provided a clearer picture of the trapping–detrapping phenomena in the Al
0.25Ga
0.75N layer. The value of the border trap density extracted using the carrier-number-fluctuation (CNF) model was 1.3 × 10
19 cm
−3·eV
−1, which is of a similar level to the extracted value from the distributed circuit model.
