On the impact of buffer and GaN-channel thickness on current dispersion for GaN-on-Si RF/mmWave devices

Abstract

The GaN-on-Si technology for the upcoming RF/6G/mm-Wave applications requires a robust buffer design for enhanced device performance and improved reliability. The defect states present in the various layers of the buffer stack can have a detrimental impact on both the DC and the AC performance of the device, as they can interact with the 2DEG channel carriers and/or contribute to buffer leakage mechanisms. An important reliability concern is the dynamic-R-ON, arising from the interaction of the 2DEG channel with the defects in the buffer stack and/or the defects in the barrier layer or barrier/cap interface. In this work, an improved and more robust current transient spectroscopy technique is used to extract the time constant spectra and the activation energies of various buffer defects. A thinner GaN channel layer is shown to increase the dynamic-R-ON, while a specific buffer stack configuration is shown to have a considerable impact the dynamic-R-ON.