Impact of device geometry at different ambient temperatures on the self-heating of GaN-based HEMTs

The influence of the device geometry on the self-heating for GaN-based HEMTs was assessed at different ambient temperatures, from 25 °C to 175 °C. The results showed that the gate width can significantly affect the heat dissipation. In addition to this, the distribution of the generated heat in the channel has been demonstrated to be dependent on the distance between the gate and drain contacts. Besides the device geometry, the ambient temperature was also found to be relevant for the thermal resistance, mainly due to the temperature-dependent thermal conductivity of the layers and the substrate. The channel temperature and the thermal resistance extracted from the measurements were in good agreement with the simulations.