Improved robustness of AlGaN/GaN HEMTs using Deuterium to passivate the structural defects

GaN related devices have demonstrated excellent performances for high power, high temperature up to X-band applications. However, even if the reliability studies on AlGaN/GaN high electron mobility transistors (HEMT) have led to higher mean time to failure (MTTF), physical mechanisms induced by stresses are still not well known. This paper proposes an original solution to improve the robustness of the devices by passivating the traps that are supposed to be related to the degradation process. Based on the experience of previous works, we use Deuterium H+ to block the traps located at the AlGaN/GaN interface above the gated zone of the device, and the traps in the bulk of the conducting channel (2 dimensions electron gas : 2DEG). 2 batches of devices are processed with and without deuterium, and submitted to temperature stresses at 500degC. Low frequency noise (LFN) measurements are performed to track the evolution of the spectral current density of the drain current, which is known to be related to the structural evolution of the traps and of the crystal structure perfection. Devices with deuterium feature stable LFN spectra, while LFN spectra of the devices without deuterium evolve during the different stress steps. Thus, deuterium can offer an interesting alternative to enhance the robustness of AlGaN/GaN devices operating under stringent temperature conditions.