Investigating the Defect Structures in Transparent Conducting Oxides Using X-ray and Neutron Scattering Techniques

Abstract

Transparent conducting oxide (TCO) materials are implemented into a wide variety of commercial devices because they possess a unique combination of high optical transparency and high electrical conductivity. Created during the processing of the TCOs, defects within the atomic-scale structure are responsible for their desirable optical and electrical properties. Therefore, studying the defect structure is essential to a better understanding of the behavior of transparent conductors. X-ray and neutron scattering techniques are powerful tools to investigate the atomic lattice structural defects in these materials. This review paper presents some of the current developments in the study of structural defects in n-type TCOs using x-ray diffraction (XRD), neutron diffraction, extended x-ray absorption fine structure (EXAFS), pair distribution functions (PDFs), and x-ray fluorescence (XRF).

Transparent-conductive-oxide (TCO) buffer layer effect on the resistive switching process in metal/TiO2/TCO/metal assemblies

“…At the same time, the appreciable decrease of the main band integral intensity (including a and b peaks) depending on the material of the buffer layer, is traced and is likely to be a result of the varying oxygen content in the synthesized TiO 2 films. As follows from figure 9, the lowest intensity of this band occurs in the film grown onto an ITO layer and is likely to be a result of the formation of the film with the lowest stoichiometry during synthesis, due to the migration of oxygen ions from the TiO 2 film into ITO since the structure of ITO contains a considerable number of oxygen vacancies [43]. Additional evidence of this conjecture can be found in the second band characterized by c and d peaks and related to transitions into the empty electronic states with mixed Ti 4s, 4p + O 2p character.…”

“…As was mentioned above, the TiO 2 film grown onto the ITO buffer layer is characterized by the lowest stoichiometry compared with the film prepared onto the Al 2 O 3 /ITO buffer layer. Taking into account that the ITO layer contains a surplus of the oxygen vacancies [43] (white circles), it is reasonable to assume that the O 2− ions (green circles) will easily move from TiO 2 into the ITO layer within the interface region, under the influence of the internal electric field (this process is indicated by solid arrows). Al 2 O 3 acts as a barrier layer against arbitrary migrations of charged particles [48,49].…”

Mg acceptor doping of In2O3 and overcompensation by oxygen vacancies

“…% (corresponding to a concentration of % 1:5 Â 10 20 cm À3 ). 15 Van-der-Pauw Hall measurements at room temperature (RT) and at variable temperature, as described in Ref. 8, were performed to determine the film sheet transport properties which were converted into the average film bulk transport properties using the measured film thickness.…”

Stabilization of 2D assemblies of silver nanoparticles by spin-coating polymers

“…It is well known, for example, that the electrochemical deposition of metals on bare ITO proceeds via seeded growth, in which the metal reduction begins at defect sites, often at the boundaries between individual ITO crystallites that provide the smallest reduction overpotential. [48] Silver reduction occurred in places where a crater overlapped with such defect site. In some instances, zero silver diffused from the inside of craters forming silver clusters on the outside.…”