Large Negative Thermal Quenching and Broadening Lineshape Analysis of Acceptor-Associated Yellow Luminescence in Si-Doped GaN

The yellow luminescence (YL) is a famous acceptor associated light emission phenomenon in GaN, which is a technologically important wide-bandgap semiconductor having tremendous applications in short-wavelength optoelectronic devices and high-power/high-temperature electronic devices. However, there have been few studies on the broadening lineshape analysis and substantial negative thermal quenching of the YL band in GaN. In this article, the large negative thermal quenching (NTQ) phenomenon of the YL band in a series of Si-doped GaN samples is observed and investigated in detail under the sub-bandgap optical excitation, which is unobservable under the usual above-bandgap optical excitation. Based on rate equations of holes, a simple model is developed to quantitatively analyze the observed NTQ data, unveiling that the thermal transfer of holes excited from the shallow acceptors located at -,300 meV above the valence band maximum to the YL deep acceptors shall be responsible for the observed large NTQ in the Si-doped GaN. Above and beyond, the underdamped multimode Brownian oscillator (MBO) theory was employed to analyze the YL lineshape at 290 K. Several important physical parameters governing the YL process, such as the Huang-Rhys factor, zero-phonon line location, dissipating coefficient of acoustic phonon bath, etc., were thus determined. The YL deep acceptor level was estimated to be located at -,840 meV above the valence band maximum.

Automated summary

This article investigates the phenomenon of negative thermal quenching in the YL band of Si-doped GaN and concludes that it is caused by the thermal transfer of excited holes from shallow acceptors to deep acceptors. The YL lineshape is analyzed, and important physical parameters related to the YL process are determined. The position of the YL deep acceptor level is estimated.