Investigation of trap states in Al2O3 InAlN/GaN metal–oxide–semiconductor high-electron-mobility transistors

In this paper the trapping effects in Al2O3/In0.17Al0.83N/GaN MOS-HEMT（here, HEMT stands for high electron mobility transistor） are investigated by frequency-dependent capacitance and conductance analysis. The trap states are found at both the Al2O3/In AlN and InAlN/GaN interface. Trap states in InAlN/GaN heterostructure are determined to have mixed de-trapping mechanisms, emission, and tunneling. Part of the electrons captured in the trap states are likely to tunnel into the two-dimensional electron gas（2DEG） channel under serious band bending and stronger electric field peak caused by high Al content in the In AlN barrier, which explains the opposite voltage dependence of time constant and relation between the time constant and energy of the trap states.