Huge Photoresistance in Transparent and Conductive Indium Titanium Oxide Films Prepared by Electron Beam–Physical Vapor Deposition

Abstract

Transparent and conductive indium titanium oxide (ITiO) films have been obtained by electron beam physical vapour deposition with Ti content from 5 at % up to 28 at %. X-ray absorption spectroscopy techniques have been used to identify the local environment of Ti ions. Even at the lowest concentrations Ti is not incorporated into the In 2 O 3 structure but forms clusters of a Ti−In mixed oxide that present a distorted rutile TiO 2 short-range order. The optical transmittance of the annealed samples reaches 95 % and no significant variation of the gap energy (around 3.7 eV) is observed with Ti content. The electronic conductivity under light irradiation is studied evidencing a huge photo-resistance in the samples with Ti content above 22 at % reaching more than two orders of magnitude for the 26 at % Ti under illumination with few μW/cm 2 at 365 nm. Hall and conductivity results are analyzed using a model that takes into account both electron and hole carriers as well as the conductivity enhancement by carrier photogeneration. The electron carrier density decreases with Ti content while its mobility increases up to values of 1000 cm 2 /(V s). Oxygen annealed ITiO films obtained by this technique with Ti content below 10 at % have properties adequate as transparent semiconductors and those with Ti content higher than 22 at % have exceptional photoresistive properties relevant for numerous applications.

Probing the effects of thermal treatment on the electronic structure and mechanical properties of Ti-doped ITO thin films

“…Novel ITO composites doped with 3-d and/or 4-d transition metals, such as (Ti, Ag, Cr, Mo, W, Ta and Cu), are being considered as potential candidates in a wide range of optoelectronic applications such as organic and inorganic solar cells, touch screens, organic light-emitting diodes, sensors and electro-chromic devices [19][20][21][22][23][24]. In order to satisfy the demands for some of these applications, TCO composites with improved durability are required.…”

The Ampoule Method: A Pathway towards Controllable Synthesis of Electrocatalysts for Water Electrolysis

“…The controllable synthesis of electrocatalysts for water electrolysis is an ongoing technological challenge for renewable hydrogen production. [1][2][3][4][5] Althoughn umerousm ethods for the synthesis of materials have been developed, including thermal routes, [6][7][8] chemical/physical vapor deposition, [9,10] atomicl ayer deposition, [11] exfoliation, [12] sol-gel, [13] combustion, [14] microwave-induced, [15] electrochemical, [16] and laser synthesis, [17] they suffer from unmanageabler eactionc onditions, environmental impact,a nd complicated device configuration. Therefore, the controllable synthesis of water electrolysis catalysts through a simple methodw ith accessible devices and controlled environment is highly desirable.…”

Improving the optoelectronic properties of titanium-doped indium tin oxide thin films

“…Amongst this family of materials,ITO has a large number of favourable properties such as low electrical resistivity, high transparency in the visible light region, great film-substrate adhesion and good chemical stability. Therefore, ITO films are of great interest and represent the prime candidate for numerous applications in optoelectronic devices such as flat panel displays, solar cells, organic light-emitting diodes, sensors, functional glass and electro-chromic devices [4][5][6][7][8][9][10][11]. Numerous techniques are employed for synthesizing ITO films such asDC and RF magnetron sputtering, thermal evaporation, pulsed laser deposition, electron beam evaporation, screen printing and sol-gel processes [12][13][14][15][16].…”