Micro‐Raman scattering spectroscopy study of Li‐doped and undoped ZnO needle crystals

Abstract

ZnO nanostructures have attracted great attention for possible applications in optoelectronic and spintronic devices. The electrical resistivity because of carriers can be improved by the introduction of Li ions, as Li is a possible dopant for achieving p-type ZnO. We have carried out a comprehensive micro-Raman scattering study of the phonons in 1% Li-and undoped ZnO needle crystals grown and annealed at 1073 K for 1 and 2 h under oxygen environment. Phonon mode of doped and undoped ZnO does not show any measurable shift for the doping concentration of 1%. As line width is related to point defect density, we find for both Li-and undoped ZnO crystals the crystallinity is improving towards the tip of the needle crystals.

Photocatalytic Activity and Selectivity of ZnO Materials in the Decomposition of Organic Compounds

“…The Raman spectra were consistent with that of standard wurtzite ZnO; [28,29] in detail, Raman modes A-D originated from second-order E 2 -low, second-order A 1 -TO, firstorder A 1 -TO, and first-order E 2 -high wurtzite ZnO, respectively. [28] Importantly, Li 2 O typically exhibits a Raman mode at about 523 cm À1 (F 2g mode), [30,31] which was absent from the Raman spectra of Li-doped ZnO, thus further substantiating the successful doping of Li in the ZnO lattice. These Raman observations were consistent with the XRD results that no major changes in the crystal structure (e.g., bulk crystallinity) had occurred on doping with Li.…”

“…e) Raman spectra; Raman modes A-D originated from second-order E 2 -low, second-order A 1 -TO, first-order A 1 -TO, and first-order E 2 -high wurtzite ZnO, respectively. [28] . f) UV/Vis absorption spectra.…”

Cesium doped and undoped ZnO nanocrystalline thin films: a comparative study of structural and micro‐Raman investigation of optical phonons

“…The strong E 2 (high) mode indicates very good crystallinity. [26] For the samples annealed at 800 • C, additional peaks have been detected in the Raman spectra. The additional peaks could be assigned to the combination modes such as A 1 (LA + LO) (longitudinal acoustic + longitudinal optical), A 1 (2 TO + 1 LO) and 2E 2 (low) + 4 LO, as shown in Fig.…”

Synthesis and optical properties of ZnO and ZnO/PEO nanonsructured powders

“…Iz literature je poznato da intenzivna traka E2H moda ukazuje na dobru kristaliničnost ZnO [23], što je u slučaju mikrotalasno procesiranog ZnO praha u skladu sa XRD podacima. Traka malog intenziteta na oko 410 cm -1 potiče od E1 (TO) moda iukazuje da kristaliti ZnO ne rastu preferentno duž c-ose.…”