Sn-Doped CdS Nanowires with Low-Temperature Lasing by CW-Laser Excitation

Sn-doped CdS nanowires, with the inside coexisting Sn(II)S, Sn2(III)S3, and Sn(IV)S2 identified by in situ Raman and XPS spectra, are grown via a simple thermal evaporation deposition technique. Its room-temperature photoluminescence (PL) spectrum shows a broad in-gap emission band out of different Sn dopants which is also superposed by a series of weak modes from a microcavity due to the wire size and its structure, besides the CdS band-edge emission and a side-band emission due to SnS2. The ratio of the intensity of the in-gap emission versus that of the band-edge emission is only 1/4 at room temperature, but it can be remarkably increased to about 7 at 80 K. This significant enhancement of the in-gap emission may be attributed to the local plasma coming from more bound carriers and enhanced microcavity effect at low temperature by analyzing the temperature-dependent PL and Raman spectra in detail. For these reasons, the band-edge and in-gap emission both can realize lasing excited by a continuous laser at 80 K. The results would provide a way to get temperature tunable low threshold microscale lasers and study the plasma-polariton process within a microcavity.