Interface traps at Al2O3/InAlN/GaN MOS-HEMT-on-200 mm Si

We report on the characterization of the interfaces of Al₂O₃/InAlN/GaN HEMT structure grown on 200 mm diameter silicon using conductance dispersion technique. Irreversible threshold voltage (V_TH) shift of up to +∼2.5 V was observed due to the gate stress induced activation of acceptor states. Further, frequency dependent V_THshift during capacitance voltage measurements were also recorded due to the presence of slow traps at InAlN/GaN interface. The conductance dispersion indicated the presence of acceptor traps of the order of ∼4 × 10¹² to 7 × 10¹³ cm⁻² eV^-1 with a time constant of ∼10 to 350 μs at the InAlN/GaN interface. Trap density at the Al₂O₃/InAlN was found to be in similar range but with a time constant of ∼2 µs. The presence of high density of traps at InAlN/GaN interface is attributed to the unavoidable growth interruption before the start of InAlN growth.