Electron-hole plasma Fabry-Perot lasing in a Ga-incorporated ZnO microbelt via Ag nanoparticle deposition

In this work, individual ZnO via Ga-doped (ZnO:Ga) microbelts with excellent crystallinity and smooth facets can enable the realization of lateral microresonator Fabry-Perot (FP) microlasers, and the F-P lasing action originates from excitonic state. Interestingly, introducing Ag nanoparticles (AgNPs) deposited on the microbelt can increase F-P lasing characteristics containing a lower threshold and enhanced lasing output. Especially for the large size AgNPs (the diameter d is approximately 200 nm), the lasing features also exhibit a significant redshift of each lasing peak and an observable broadening of the spectral line width with an increase of the excitation fluence. And the remarkable lasing characteristics are belonging to the electron-hole plasma (EHP) luminescence. The behavior and dynamics of the stimulated radiation in an AgNPs@ZnO:Ga microbelt are studied, suggesting the Mott-transition from the excitonic state to EHP state that is responsible for the F-P lasing. These features can be attributed to the working mechanism that the hot electrons created by the large size AgNPs through nonradiative decay can fill the conduction band of nearby ZnO:Ga, leading to a downward shift of the conduction band edge. This novel filling influence can facilitate bandgap renormalization and result in EHP emission. The results provide a comprehensive understanding of the transition between excitonic and EHP states in the stimulated emission process. More importantly, it also can provide new scheme to developing high efficiency and ultra-low threshold microlasing diodes. (C) 2022 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

In this work, individual ZnO microbelts doped with Ga (ZnO:Ga) were studied for their applicability in lateral microresonator Fabry-Perot (FP) microlasers. Introducing Ag nanoparticles (AgNPs) on the microbelts improved the FP lasing characteristics, including lower threshold and enhanced output. Notably, large AgNPs showed a redshift and broadening of lasing peaks with increasing excitation fluence. The stimulated radiation in an AgNPs@ZnO:Ga microbelt was attributed to the Mott transition from excitonic state to electron-hole plasma (EHP) state. This study provides insights into the transition between excitonic and EHP states and offers a new approach for developing high-efficiency and ultra-low threshold microlasing diodes.