Fine Structure of Ultraviolet Photoluminescence of Tin Oxide Nanowires

Abstract

Photoluminescence (PL) properties of tin oxide (SnO 2 ) nanowires are studied in detail using high spectral resolution spectroscopy in a temperature range of 10-300 K. The nanowires have an average diameter of 86 nm. The high quality of the nanowires enables the observation of rich fine structures in the ultraviolet PL spectra at low temperatures. By carefully analyzing the temperature and excitation power dependent spectra, the following emissions are identified: recombination of donor-acceptor pairs, excitons bound to neutral and ionized donor impurities and optical transitions from free electrons to neutral acceptor impurities. Moreover, it is believed that the emission from recombination of free excitons is observed, which is unusual for SnO 2 , a dipole forbidden direct band gap semiconductor.

Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices

“…The absorption tail evidences the formation of a phase with E g~3 .6 eV consistent with SnO 2 nanoprecipitation. The PL spectrum excited at 4.1 eV shows two distinct contributions, both in the UV spectral region, due to radiative recombination of SnO 2 -free excitons at ~3.6 eV (FX, cyan band) and to radiative decay of excitons in donor-acceptor sites 33,50 at ~3.3 eV (pink band). Importantly, in this excitation condition, no emission from Snrelated oxygen deficiency centres (ODCs) 49 or SnO 2 defects in the visible spectral region is observed.…”

“…49) and the superposition of several contributions recently attributed to exciton bound to neutral donor (D 0 X) and donor-acceptor pair (DAP) recombinations 33,50 with a total FWHM of 0.13 eV. In regard to SnO 2 in lowdimensional systems, the strong quantum confinement causes the E g to shift towards higher energies and enables free-exciton decay (FX) 32,36 at 3.5-4 eV with a FWHM of 0.53 eV.…”

“…Most relevant for this discussion, band-edge excitonic emission at 320-360 nm (refs 6,32,33) and radiative recombination mediated by shallow traps emitting at 370-390 nm (ref. 33) have been observed for a variety of SnO 2 nanostructures, such as colloidal suspensions 32 , nanowires 33 , NC films 34 , NCs embedded in silica by ion implantation 35 and thermally grown nanophase by selective nucleation of the molecular precursors in sol-gel silica 36 . The latter synthesis strategy opened the way to a possible design of robust UV-emitting structures based on NS SnO 2 :SiO 2 films spin-coated on silicon substrate, with benefits derived from a solution-based method, a full compatibility with existing silicon technology, and superior environmental stability resulting from the full inorganic architecture and the incorporation of the chromophores in silica.…”

Brush-like SnO2/ZnO hierarchical nanostructure: Synthesis, characterization and application in UV photoresponse

“…46 Here, the UV emission band at 361 nm is attributed to band edge recombination of the photogenerated carriers, which may be originated from the conduction band to acceptors and neutral-donar-bound excitons. [47][48][49] For the SnO 2 nanowires sample, the above XPS result reveals that oxygen vacancies are formed on the SnO 2 nanowire surface. The oxygen vacancies can form acceptor level which results in a blue emission band at 445 nm.…”

“…Up to now, the photoluminescence mechanism of SnO 2 is still not clear. [43][44][45][46][47][48][49] It is believed that the surface oxygen vacancies defect states can induce direct gap transitions and generate possible photoluminescence. [43][44][45] Recently, Li et al found that that the SnO 2 nanostructures can break the dipole-forbidden rule and realize UV luminescence.…”