Effect of quantum confinement on polarization anisotropy emission in Sn-doped CdS microcones

Abstract

Polarization anisotropy of emission, which carriers a lot of effective information that cannot be obtained from light intensity, wavelength, frequency and phase, is promising for multifunctional applications ranging from optical communication to spectroscopy analysis. The manipulation of polarization emission at room temperature is essential for spintronic applications. However, most of the high degree polarization is achieved at cryogenic temperatures or using sophisticated epitaxial techniques. Here, we prove the relationship between the cross-section radius and polarization ratio, and demonstrate the maximum polarization ratio is about 60% when the cross-section radius is 1.15 μm in a Sn-doped CdS microcone. Time-resolved PL spectra provide insight into radiative contributions to the observed polarization emission. In addition, the emission peak of free exciton A (FXA) is blue-shifted with the decrease of cross-section radius, which proves that the quantum confinement effect plays an important role in the observed polarization anisotropy emission. Our work provides a promising approach to achieve room temperature high-spin polarization, which contributes to spin-photonics applications.