Exciton magnetic polarons (EMPs) are self-organized magnetic quasiparticles that can be formed by excitons in diluted magnetic semiconductors (DMSs). The optical response of EMPs in DMS microstructures is not yet well understood because it is affected by many competing factors, including spin-dependent exchange interactions, phonon coupling, and collective and nonlinear effects upon the dopant concentration and structural relaxation. Here, we report on lasing from collective EMP states in Co­(II)-doped CdS nanowires (NWs) and nanobelts (NBs) that we interpret in terms of bosonic lasing, the spontaneous emission of radiation by a single quantum state macroscopically populated by bosonic quasiparticles. The lasing threshold coincides with the appearance of ferromagnetic domains, indicating an important role of spin ordering in the formation of coherent collective EMPs. These results pave the way to the realization of a new type of bosonic laser, different from exciton-polariton lasers, where formation of the bosonic condensate is possible due to the coupling of EMPs via the exchange interaction of exciton and magnetic ion spins.

Tunable optical emission properties from ferromagnetic semiconductors have not been well identified yet. In this work, high-quality Mn(II)-doped CdS nanowires and micrometer belts were prepared using a controlled chemical vapor deposition technique. The Mn doping could be controlled with time, precursor concentration and temperature. These wires or belts can produce both tunable redshifted emissions and ferromagnetic responses simultaneously upon doping. The strong emission bands at 572, 651, 693, 712, 745, 768, 787 and 803 nm, due to the Mn(II) (4)T1((4)G)  → (6)A1((6)s) d-d transition, can be detected and accounted for by the aggregation of Mn ions at Cd sites in the CdS lattice at high temperature. These aggregates with ferromagnetism and shifted luminescence are related to the excitonic magnetic polaron (EMP) and localized EMP formations; this is verified by ab initio calculations. The correlation between aggregation-dependent optical emissions and ferromagnetic responses not only presents a new size effect for diluted magnetic semiconductors (DMSs), but also supplies a possible way to study or modulate the ferromagnetic properties of a DMS and to fabricate spin-related photonic devices in the future.

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In this work, we report the synthesis of high-quality Ni-doped CdS nanoribbons via chemical vapor deposition (CVD) method. The as-synthesized samples were characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) techniques. The presence of Ni ions in CdS nanoribbons has been confirmed through energy-dispersive X-ray spectroscopy (EDX) and nonuniform peak shifting of Raman spectrum. Except the bandedge emission, the photoluminescence (PL) properties of Ni-doped CdS nanoribbons are dominated by a broad near-infrared (IR) emission band centered around 1.61 eV. This transition corresponds to two high levels of d electronic state of Ni with strong p-d hybridization between Ni ions and S, which seldom happens in usual dilute magnetic semiconductors (DMS). The p-d hybridization is confirmed by the simulation of electronic band structure in Ni-doped CdS wires with first-principle calculation and PL lifetime measurements, which blocked the optical transitions of lowest d levels. This near-IR emission shift with varied dopant concentration in Ni-doped CdS nanoribbons has been observed for the first time in this CdS semiconductors, which could be accounted for by the quantum confinement effect of NiS cluster in CdS; this material may be used as nanoscale light sources tuned by the dopant, possibly for solar cell if highly doped.

Schottky-barrier diodes have great importance in power management and mobile communication because of their informal device technology, fast response and small capacitance.

Using a simple in situ seeding chemical vapor deposition (CVD) process, comb-like (branched) monolithic CdS micro/nanostructures were grown. Efficient optical coupling between the backbone and the teeth of the branched architecture is demonstrated by distributing light from an UV-laser-excited spot at one end of the backbone to all branch tips. By varying the deposition conditions, the orientation of the branches with respect to the backbone, their size and density can be tuned as well as the size of the backbone. This in situ seeding CVD method has the potential for a low-cost single-step fabrication of high-quality, micro/nanointegrated photonic devices, with tunable complex waveguiding possibilities.

A doping technique achieved remarkable success in improving the electrical and semiconductor-to-metal transitions characteristics of WS2 FET.

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