Activation energy of traps in GaN HFETs

Low frequency noise characteristics of GaN/AlGaN HFET structures grown either on sapphire or SiC substrates were measured in wide temperature range 13 K to 300 K and activation energy of traps determined by several methods around 0.42 eV (SiC) and 63 meV (sapphire). Conceptual approach to trap parameters estimation was tested on RTS noise time-trace. The Hooge parameter alpha of GaN/AlGaN on SiC HFETs was of the order of 10-4to 10-5, whereas two orders higher values for sapphire based devices were given by strong g-r noise.