Temperature‐Dependent Transition in the Dominant Nonradiative Carrier Recombination Process in Ultrathin AlN/GaN/AlN‐Quantum Wells Studied by Phononic–Excitonic–Radiative Model

The analysis of the activation mechanism of the nonradiative electron–hole recombination (NRR) process is a crucial issue in improving the radiation efficiency of light‐emitting devices. This article shows the mechanism determining the functional feature of the dependence of NRR rate in quantum wells (QWs) on temperature, taking an example of ultrathin AlN/GaN(one molecular layer)/AlN QW. An analysis is conducted by introducing exciton and free‐carrier NRR channels to the 2D phononic–excitonic–radiative model, including carrier injection, recombination, electron collisional, and phononic excitation and de‐excitation transfer of excitonic states. The exciton and free‐carrier NRR processes, the activation energy of the NRR process, and the exciton binding energy are the parameters of the dependence. It is found that the population distribution in the exciton system is a crucial factor for the dependence of the NRR rate on temperature. The experimentally observed almost constant or weak decrease in the NRR rate with increasing temperature in the vicinity of 300 K is attributed to the rate balance between exciton and free‐carrier processes. The reason for the nearly constant feature and faint decrease in the low‐temperature region remains covered; the energy‐dependent cross‐sectional feature of low‐velocity excitons and the nonthermal electron–lattice system are required to be studied.