Low 1/f noise in AlGaN/GaN HFETs on SiC substrates

Experimental results of the low-frequency noise measurements on a large number of different AlGaN/GaN High Electron Mobility Transistors (HEMTs) grown on sapphire and SiC substrates have been presented. In the HEMTs grown on sapphire, the 1/f noise is an order of magnitude (or more) higher than for AlGaN/GaN HEMTs grown on SiC substrates. The devices on SiC substrates also have higher electron mobility compared to the devices grown on sapphire substrates. The temperature dependence of noise reveals a contribution to the noise from a local level with activation energy of approximately 0.42 eV for the structures grown on sapphire. A very weak temperature dependence of the low-frequency 1/f noise found for the wafers grown on SiC is very important for high temperature applications of these devices.