Trap behaviors in AlGaN/GaN based polarization-doped field effect transistors by frequency-dependent conductance–voltage characterizations

• The trap behaviors of PolFETs were first systemically evaluated.
• No obvious effective traps accumulation in the graded heterojunctions of PolFETs.
• Exactly exponential dependence of trap time constants on bias voltage was observed.

AlGaN/GaN polarization-doped field-effect transistors (PolFETs) were fabricated on the graded AlGaN/GaN heterojunctions grown by metal organic chemical vapor deposition, and the trap behaviors were first systemically evaluated by frequency-dependent conductance–voltage characterizations. It was found that there was no obvious effective traps accumulation in the graded AlGaN/GaN heterojunctions of the PolFETs due to the absence of abrupt heterostructure as in the traditional HFETs. The exactly exponential dependence of the trap state time constants on the bias voltage in PolFETs was observed, which was a typical characteristic for interface traps, indicating a multi-heterointerface feature of the PolFETs.