Relaxation of conductivity in AlGaN/AlN/GaN two-dimensional electron gas at high electric fields

AlGaN/AlN/GaN heterostucture with a very thin (0.6 nm) AlN spacer was investigated by conductivity relaxation measurements after a strong electric field action. To obtain the two-dimensional electron gas (2DEG) channel transport properties at high electric fields the relaxation results were extrapolated to the time of the peak of an applied nanosecond high-voltage electric pulse. Significant decrease of hot electron sheet density at high electric fields was revealed. The measured sample conductivity relaxation is decided not only by the changes of 2DEG channel conductivity due to variation of sheet density. This does not allow one to obtain corrected drift velocity values at high electric fields. The obtained results show that the AlN thickness must be more than 0.6 nm.