Solid solubility of rare earth elements (Nd, Eu, Tb) in In_2−xSn_xO₃ – effect on electrical conductivity and optical properties

Abstract

Wide band-gap semiconductors doped with luminescent rare earth elements (REEs) have attracted recent interest due to their unique optical properties. Here we report on the synthesis of the transparent conducting oxides (TCOs) indium oxide and indium tin oxide (ITO) doped with neodymium, europium and terbium. The solid solubility in the systems was investigated and isothermal phase diagrams at 1400 °C were proposed. The solubility of the REEs in In2O3 is mainly determined by the size of the rare earth dopant, while in ITO the solid solubility was reduced due to a strong tendency of the tin and REE co-dopants to form a pyrochlore phase. The effect of the REE-doping on the conductivity of the host was determined and optical activity of the REE dopants were investigated in selected host materials. The conductivity of sintered materials of REE-doped In2O3 was significantly reduced, even at small doping concentrations, due to a decrease in carrier mobility. The same decrease in mobility was not observed in thin films of the material processed at lower temperatures. Strong emissions at around 611 nm were observed for Eu-doped In2O3, demonstrating the possibility of obtaining photoluminescence in a TCO host, while no emissions was observed for Nd- and Tb-doping.

Structural, Electrical, and Optical Properties of the Tetragonal, Fluorite-Related Zn0.456In1.084Ge0.460O3

“…Hall measurements show that nonreduced ZIGO1 has a bulk carrier concentration of 4.772 × 10 14 cm −3 , which is in the same order as In 2 O 3 thin films and lower than reduced In 2 O 3 . 53,54 Hall measurements of the ZIGO1 samples indicate that they have n-type conductivity, which is consistent with the bixbyite Zn−In−Ge−O phases of Cheng et al and In-containing TCOs in general. 24 The average room temperature conductivity of ZIGO1 is 0.08(1) S·cm −1 before hydrogen reduction and 147(4) S·cm −1 after reduction.…”

“…These values are either comparable or superior to the conductivity of In 2 O 3 , as reported values display a wide degree of variation. 10,54 This is also of the same order of magnitude as the conductivity values for Zn x In 2−2x Sn 2 O 3 , if the conductivity trend of the Zn x In 2−2x Sn 2 O 3 system is extrapolated to the same percent In composition (x > 0.4 yields secondary phases in Zn x In 2−2x Sn 2 O 3 , but x = 0.458 corresponds with the % In in ZIGO). 53 The low conductivity is partially a result of the low doping inherent in this material, as the offstoichiometry of Zn and Ge result in a Ge 4+ dopant of 0.2%.…”

Recent Progress and Emerging Applications of Rare Earth Doped Phosphor Materials for Dye‐Sensitized and Perovskite Solar Cells: A Review

“…Lanthanide doped up/down conversion materials can be synthesized easily at low temperatures and they found various applications such as transparent conducting oxide (TCO), tandem solar cells, photocatalysis, water splitting, drug delivery systems and so on. Optical properties of the TCOs can be finely tuned by doping luminescent rare earth elements into the wide band gap semiconductors (FTO or ITO) that results in improving their electrical property . Coming to tandem solar cells, application of these lanthanide doped materials as scattering layers reduces the defect centres carriers i. e.thermalization losses which inturn enhances the device efficiency .…”

“…Optical properties of the TCOs can be finely tuned by doping luminescent rare earth elements into the wide band gap semiconductors (FTO or ITO) that results in improving their electrical property. [156] Coming to tandem solar cells, application of these lanthanide doped materials as scattering layers reduces the defect centres carriers i. e.thermalization losses which inturn enhances the device efficiency. [157] when these rare earth doped luminescent materials are coupled with commercially available wide band gap semiconductors such as TiO 2 , it helps in fast degradation of inorganic and organic pollutants and water splitting under visible light irradiation.…”

Site Identity and Importance in Cosubstituted Bixbyite In2O3

“…In the original investigation, the samples were air quenched, but reduction treatments of n-type TCOs are common practices for increasing oxygen defects and therefore the conductivity and had not yet been performed. The room temperature conductivity of Mg x In 2−2x Sn x O 3 before and after such a reduction procedure is shown in Figure 3 [27]. The conductivity of as-synthesized Mg x In 2−2x Sn x O 3 was previously reported to be on the order of 10 0 Ω · cm (equivalent to 10 0 S/cm), but here, the conductivity of the as-synthesized Mg x In 2−2x Sn x O 3 ranges from 5.8 × 10 1 S/cm −1 to 1.56 × 10 2 S/cm −1 , which are orders of magnitude greater.…”