Surface polarons and optical micro-cavity modulated broad range multi-mode emission of Te-doped CdS nanowires

Abstract

The optical confinement and strong carrier coupling within a semiconductor nanostructure cavity are crucial for the modulation of emission properties. Fundamental understanding of the light-matter interaction in a low dimensional system is important. In this paper, we synthesized high-quality hexagonal Te-doped CdS nanowires by two-step chemical vapor deposition and investigated systematically the doping concentration, temperature, excitation power, excitation wavelength dependent Raman, photoluminescence and carrier lifetime decay. Scanning electron microscopy, energy dispersive x-ray spectrometry and x-ray diffraction confirmed Te-doping in the as-prepared samples. The strong surface optical (SO) phonon mode is observed in the micro-Raman spectra of an individual Te-CdS nanowire, which is unsuitable in large-sized structures. In situ micro-photoluminescence (μ-PL) characterization shows dominant confined defect state emission with whispering gallery mode (WGM) characteristics. The emission peak position shifts under increased excitation power, demonstrating the inelastic scattering by bound carriers. In addition, the short wavelength emission modes are dominant at a low temperature (80 K) while the long wavelength emission modes are dominant at a high temperature (300 K) due to different recombination processes contributing to the WGM resonant bands, which was also confirmed by the time-resolved PL measurement. All these results reflect strong coupling between the surface evanescent-wave in the WGM cavity and the SO phonon/polaron, which will facilitate the rational tailoring of surface/interface relevant properties for nanophotonic device applications.

Bulk Assembly of Zero-Dimensional Organic Copper Bromide Hybrid with Bright Self-Trapped Exciton Emission and High Antiwater Stability

“…Clearly, the emission band position undergoes a consecutive red-shift at higher temperatures. This phenomenon is consistent with the previously reported common semiconductor of CdS and ZnSe, which is caused by the band gap shrinkage as a result of the enhanced electron–phonon coupling at higher temperatures, and the similar phenomenon also appears in the recently reported lead-free metal halide of (C 4 H 14 N 2 ) 2 In 2 Br 10 . Moreover, FWHM becomes narrow with the decrease of temperature (Figure c), which usually means the decreased electronic coupling with acoustic phonons …”

Optical and Optoelectronic Performances of Quasi-Rectangular Cross-Sectional Sn-Doped CdS Nanowires

“…Similar to the single exponential decay trend of our previously reported CdS nanowire, the decay trend of quasi-rectangular cross-sectional Sn-doped CdS nanowire also shows single exponential decay. The PL intensity fitted by the Arrhenius equation is given as follows , where I ( T ) and I (0) are the PL intensities at temperature of T and 0 K and E is the activation energy. As the fitting solid line shown in Figure d, the fitted E = 43.01 meV, which is comparable with the thermal energy for dissociation of the free exciton.…”

Surface/Interface Engineering for Constructing Advanced Nanostructured Light-Emitting Diodes with Improved Performance: A Brief Review

“…Modifying the core-shell structure is another method to overcome the total internal reflection at the semiconductor and air interface, improve the escape probability of the light, and consequently increase the light extraction efficiency [70,71], as shown in Figure 4. Zhang, Yao, and Zheng's team used the high directionality of waveguide mode transmission and the efficient energy transfer of localized surface plasmon (LSP) resonances to increase the spontaneous emission rate of LEDs, respectively [72][73][74].…”