Influence of Cu ions on the photo‐transport properties in KTaO₃:(Cu,V) single crystals

Abstract

Photoconductivity kinetics, temperature dependence and excitation spectra were measured in the intervals 15-300 K and 2-4.2 eV in KTaO 3 :(Cu,V) single crystals processed by oxidation/reduction treatments. The kinetics, excited by band-gap excitation, present very slow saturation times, while faster time responses were observed using excitation below the band-gap. The oxidized crystal exhibited higher photoconductivity when E light > 3 eV. Linear dependence on light intensity was measured, suggesting one center recombination processes. Optical absorption at room temperature was checked as complementary information.

Optical spectroscopy characterization of Cu doped ZnO nano- and microstructures grown by vapor-solid method

“…In particular, for the range below 3.18 eV (390 nm) lines at 5.8, 4.65, 4.6, 4.31, 3.67 and 3.36 eV (213.3, 266.5, 270.2, 287.9, 337.8 and 368.6 nm)have been observed. On the other hand in the work of Rossella et al[21] a photocurrent peak in ZnO:Cu has been reported, which could be related to these emission. Regarding the less doped sample of this series, it shows both a peak at 2.9 eV which is usually related to surface effects or dislocations in ZnO[22,23] and the characteristic green emission of ZnO, about 2.36 eV usually attributed to defects such as oxygen vacancies[24], even if much weaker, the yellow-orange emission typically associated with the presence of Zn vacancies[25], it is also visible.…”

A novel contractive effect of KTaO3 nanocrystals via La3+ doping and an enhanced photocatalytic performance

“…However, it was their wide band gap the tantalates are usually less active under visible-light irradiation. Ion doping is usually employed not only to extend the light response but also to enhance the photocatalytic activity [11][12][13][14][15]. Kudo and co-workers reported lanthanum-doped sodium tantalate (NaTaO 3 ) combined with NiO as a cocatalyst, which currently holds the record of highest quantum yield for direct photolysis of water under ultraviolet light.…”

“…It found that Na ion plays an important role in K 1Àx Na x TaO 3 on both optical properties and internal electronic structure [11]. The photo-transport properties and charge trapping phenomena in KTaO 3 single crystals doped with Cu and V were investigated [13]. The copper ions doped at the Ta 5+ sites in two different charge states Cu 2+ and Cu + , produce a charge deficit compensated by oxygen vacancies.…”

In-Situ Growth of Au on KTaO3 Sub-Micron Cubes via Wet Chemical Approach for Enhanced Photodegradation of p-Nitrophenol

“…Potassium tantalates and their derivatives are wide-band gap semiconductors that are extensively applied in many fields, including gas phase condensation, photo-transporting, photo-detector, air-treatment, photo-conducting and photo-electronic response [1,2,3,4,5,6]. Furthermore, potassium tantalates are considered one kind of the most stable photoelectric catalysts and are widely employed in photonically-driven CO 2 reduction [7,8], water splitting and hydrogen evolution [7,8,9,10].…”