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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/InAlN 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 InAlN barrier, which explains the opposite voltage dependence of time constant and relation between the time constant and energy of the trap states. [ABSTRACT FROM AUTHOR]

We report Al0.30Ga0.70N/GaN/Al0.07Ga0.93N double heterostructure high electron mobility transistors with a record saturation drain current of 1050 mA/mm. By optimizing the graded buffer layer and the GaN channel thickness, both the crystal quality and the device performance are improved significantly, including electron mobility promoted from 1535 to 1602 cm2/V·s, sheet carrier density improved from 0.87×1013 to 1.15×1013 cm−2, edge dislocation density reduced from 2.4×109 to 1.3×109 cm−2, saturation drain current promoted from 757 to record 1050 mA/mm, mesa leakage reduced by two orders in magnitude, and breakdown voltage promoted from 72 to 108 V. [ABSTRACT FROM AUTHOR]