Improved transport properties and mechanism in recessed-gate InAlN/GaN HEMTs using a self-limited surface restoration method.

The etching process of high-performance recessed-gate InAlN/GaN high-electron mobility transistors (HEMTs) has been actively researched. This paper proposes a post-etching self-limited surface restoration method that effectively suppresses the etching damage, enhancing the transport properties of recessed-gate InAlN/GaN HEMTs. We fabricated planar-gate devices, inductively coupled plasma (ICP)-etched devices, and post-etching-treated (PET) devices. The damage caused by the ICP etching process severely deteriorated the transport properties of the devices. However, the post-etching process effectively inhibited the etching damage and improved the device transport properties. Through temperature-dependent tests and a simulation, the change in the peak transconductance was compared among different devices. The temperature-dependent optical phonon scattering and impurity-dependent remote charge scattering mechanisms were analyzed. The results confirmed that the etching damage significantly affected the channel electron scattering mechanism. The field-effect mobility showed a linear relationship with temperature, and the optical phonon scattering model illustrated that the field-effect mobility decreased with increasing temperature. The etching damage caused a decrease in the field-effect mobility from 1075.5 to 699.1 cm²/V·s, which increased the fitting error between this empirical line and the optical phonon scattering fitting curve from 0.086 to 0.948, similar to the remote charge scattering fitting curve. The combined error range is from 0.896 to 0.054. [ABSTRACT FROM AUTHOR]