Channel length dependence of the formation of quantum dots in GaN/AlGaN FETs

Quantum dots can be formed in simple GaN/AlGaN field-effect-transistors (FETs) by disordered potential induced by impurities and defects. Here, we investigate the channel length dependence of the formation of quantum dots. We observe decrease of the number of formed quantum dots with decrease of the FET channel length. A few quantum dots are formed in the case with the gate length of 0.05~$\mu$m and we evaluate the dot parameters and the disordered potential. We also investigate the effects of a thermal cycle and illumination of light, and reveal the change of the disordered potential.