Feature Article: Hot phonons in GaN channels for HEMTs

In the Feature Article [1] a fluctuation technique is used to obtain the hot electron energy relaxation time (blue symbols in the cover picture) and the hot phonon lifetime (red) for a biased two‐dimensional channel in an AlGaN/AlN/GaN heterostructure as a function of the supplied electric power. The close proximity of red and blue symbols illustrates that the relaxation is mainly determined by the phonon conversion into other vibrational modes being able to drain the Joule heat out of the channel. The red inset shows the momenta of hot phonons launched by hot electrons. The green line presents the electron energy relaxation time obtained by Monte Carlo simulation for lightly doped GaN under the assumption that hot phonons are absent. A strong effect of hot phonons on the electron energy relaxation is evident. The author Arvydas Matulionis is Professor of Physics and head of the Fluctuation Research Laboratory of the Vilnius Semiconductor Physics Institute. He investigates hot electron fluctuations and other high electric field effects in semiconductor heterostructures for microwave electronics. The Editor's Choice “Anomalous charge relaxation in channels of pentacene‐based organic field‐effect transistors: a charge transient spectroscopy study” by I. Thurzo et al. [2] is also part of the present issue.