Mid-Infrared Emission of Transition Metal Co²⁺-Doped ZnSe Nanocrystals at Room Temperature via Hydrothermal Preparation

Abstract

A series of Co 2+ :ZnSe and Co 2+ :ZnSe/ZnSe nanocrystals emitting mid-infrared (mid-IR) fluorescence centered at around 3.4 and 4.7 μm were successfully synthesized via a simple hydrothermal method. The core/shell structure and post-heat treatment under reducing atmosphere were adopted to decrease the nanocrystal's surface quenching centers and defects and improve the mid-IR photoluminescence. By analysis of the X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), high-resolution TEM, Fourier transform IR, absorption, and mid-IR emission measurements of serial concentrations of Co 2+ -doped ZnSe nanocrystals, the crystal phase, grain size, core/shell structure, distribution of Co 2+ ions, impurities on the surface, and mid-IR emission performance were investigated in detail. By use of optimum Co 2+ concentration, core/shell structure construction, and proper post-heat treatment, the mid-IR emission intensities of nanocrystals were enhanced by an order of magnitude, and the nanocrystals showed excellent dispersibility. These high-quality optically active nanomaterials have potential uses in mid-IR devices such as composite fiber amplifiers and hot-pressed ceramic laser materials.

Computational analysis of the optical response of ZnSe with d-orbital defects

“…Structural parameters for the doped ZnSe systems are in relatively good agreement with previous computational work and with experimental data (see table 3). For our lattice parameters, we find ∼1% deviation in comparison to experimental data [5,43,44] and <1.7% difference when comparing our results to theoretical work using PBE [45,46], or a nonlocal approach [47]. The average distance between the TM dopant and the neighbouring Se atoms also shows agreement with experiment [48] (< 0.3% deviation when compared to our results) and good agreement with PBE [49] calculations (< 2.6% deviation when compared to our results), as summarized in table 3.…”

Unveiling the Thermoelectric Performances of Zn1−xFexSe Nanoparticles Prepared by the Hydrothermal Method

“…An effective way to tune and improve the physical properties of nanostructures is through doping [1,10]. Transition-metal-doped ZnSe nanostructures have attracted great research attention as they display enhanced properties compared with their undoped counterparts for applications in spintronics and as tunable laser materials in the mid-infrared [11,12].…”

Ultrabroadband mid-infrared emission from Cr2+:ZnSe-doped chalcogenide glasses prepared via hot uniaxial pressing and melt-quenching*

“…MIR incoherent and coherent light sources are in great demand for a variety of applications in environmental testing, bioengineering, gas sensing, medical, and military industries. [1][2][3] Transition metal-doped II-VI semiconductors (TM 2+ :II-VI) [4] have emerged as an excellent gain medium for MIR femtosecond pulses [5,6] or continuously tunable lasers [7,8] owing to their ultrabroad emission and absorption bands, large emission cross-sections, and high quantum efficiency. Cr 2+ -doped ZnSe is the most representative and widely studied gain media in the TM:II-VI family.…”