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/Ga N 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 Al N and In Al N/Ga N interface. Trap states in In Al N/Ga N 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 Al N barrier, which explains the opposite voltage dependence of time constant and relation between the time constant and energy of the trap states.