Increased reliability of AlGaN/GaN HEMTs versus temperature using deuterium

Low frequency noise (LFN) is a reliable diagnostic tool to evaluate and locate the defects of a technology. In this study, LFN is used to assess effects of deuterium (H⁺ ions) in diffusion condition on the robustness of 0.25 *2*75 mum² gate area AlGaN/GaN high electron mobility transistors (HEMT) grown on Si substrate. H⁺ ions are diffused from the above AlGaN/GaN layer through the AlGaN/GaN interface and GaN layer, notably under the gated channel where the defects are located. Two batches of devices are stressed under high temperature condition at 400degC during 5 minutes (step 1) and 500degC during 15 minutes (step 2). The first batch is composed with 8 deuterated transistors while the second batch is composed with 8 non deuterated transistors. Static measurements and low frequency noise spectral density measurements of the drain current (S_ID) are examined after each step of temperature. The first step does not reveal any degradation, while the second step highlights significative differences between the deuterated and non deuterated devices: LFN of deuterated devices remains constant, whereas LFN of non deuterated devices increases (GR superimposed with 1/f flicker noise). The deuteration of the devices can open the way to robust temperature devices, as AlGaN/GaN HEMT are dedicated to applications at high power and high temperature.