The excitonic photoluminescence mechanism and lasing action in band-gap-tunable CdS1−xSex nanostructures

Abstract

Bandgap tunable semiconductor materials have wide application in integrated-optoelectronic and communication devices. The CdS_1−xSe_x ternary semiconductor materials covering green–red bands have been reported previously, but their basic band-gap and optical properties crucial to the performance of the CdS_1−xSe_x-based optoelectronic devices have not been deeply understood. In this paper, we theoretically simulated and discussed the feasibility of bandgap-tunable CdS_1−xSe_x nanomaterials for designing wavelength tunable microlasers. Then we fabricated the CdS_1−xSe_x nanobelts with their band gap ranging from 2.4 to 1.74 eV by adjusting the composition ratio x in the vapor-phase-transport growth process. The temperature-dependent photoluminescence and exciton-related optical constants of the CdS_1−xSe_x nanobelts were carefully demonstrated. Finally, the wavelength-tunable Fabry–Perot lasing in CdS_1−xSe_x nanobelts was obtained, and the Fabry–Perot lasing mechanism was numerically simulated by the FDTD method. The systematic results on the mechanism of the tunable band gap, exciton properties and lasing of the CdS_1−xSe_x nanostructure help us deeply understand the intrinsic optical properties of this material, and will build a strong foundation for future application of green–red wavelength-tunable CdS_1−xSe_x microlasers.