Investigation of defects in indium doped TiO2thin films using electrical and optical techniques

Noor Alhuda Al Saqri, Aniruddha Mondal, Jorlandio Francisco Felix, Yara Galvão Gobato, Vanessa Orsi Gordo, Hind Albalawi, Dler Jameel, Haifa Alghamdi, Faisal Al Mashary, David Taylor, Mahmmoud S. Abd El-sadek, Mohamed Henini

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9 Citations (Scopus)

Abstract

Existence of defect levels into the band gap of titanium oxide (TiO2) due to indium (In) doping was investigated by Deep level transition spectroscopy (DLTS), Raman Spectroscopy and photoluminescence (PL). Particularly, two distinct e-beam grown TiO2thin film (TF) samples on Si substrates were doped using In films with thicknesses of 5 nm and 50 nm instantaneous source. It was observed that the increasing in In doping concentration has changed the TiO2crystal structure from anatase to rutile phase. In addition, the low doped Ti/Au/5 nm In/TiO2TF samples showed at −5 V reverse-bias lower leakage current (3.0 × 10−7A) as compared to the highly doped Ti/Au/50 nm In/TiO2TF devices (7.0 × 10−5A). The free carrier concentration was increased from about 1014cm−3to 1015cm−3for 5 nm In/TiO2TF to 50 nm In/TiO2TF devices, respectively. DLTS results have revealed a unique behaviour where a substantial reduction in deep trap concentration was observed in the samples having larger In doping. A PL band around 2.4 eV and 1.9 eV was observed for 5 nm and 50 nm In/TiO2TF samples, respectively A blue shift of photoluminescence (PL) energy peak with the increase of temperature was also observed for both samples and was associated to defect related emissions. Finally, the shallow activation energy was determined from the temperature dependence of PL spectra. It was observed that the activation energy increased from 25 meV for the low In-doped TiO2TF samples to 65 meV for the highly In-doped TiO2TFs.

Original languageEnglish
Pages (from-to)883-891
Number of pages9
JournalJournal of Alloys and Compounds
Volume698
DOIs
Publication statusPublished - 2017

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Keywords

  • DLTS
  • In doping
  • I–V
  • PL
  • TiO

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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