Extraction of the interface trap density through the differential subthreshold ideality factor technique in normally-off AlGaN/GaN MOSHFETs

초록

Normally-off AlGaN/GaN-on-Si metal-oxide-semiconductor heterojunction field-effect transistors (MOSHFETs) were fabricated combining a SiO2 gate insulator and recessed-gate etching. We have studied the extraction of the sub-bandgap interface trap densities of normally-off AlGaN/GaN MOSHFETs by using the differential subthreshold ideality factor (DIF) technique. This method allows threshold-voltage (V (T) )-independent extraction of interface states by using current-voltage data in the subthreshold region. The trap density is extracted to be D (it) (E) = 1 x 10(12) similar to 3 x 10(13) [eV(-1)center dot cm(-2)] at the SiO2/GaN interface. An increase in the interface trap density was detected by the applying the DIF technique after the gate bias stress test.

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