Current instabilities in GaN-based devices

Current dispersion effects have been experimentally investigated in a varie ty, of AlGaN/GaN heterostructure FETs with large signal and switching measu rements including HEMTs with doped and undoped barrier layer, A range of di spersion frequencies from 10(-3) Hz to 10 GHz were observed, where the outp ut current amplitude is drastically reduced. Through this effect the full c hannel charge of AlGaN/GaN heterostructure FET may be completely depleted u nder specific bias conditions. This indicates that this phenomena cannot be related to deep traps alone, hut is also connected to piezo related charge states and conduction to these states.