Behavior of persistently trapped carriers induced by UV-irradiation in doped titanium dioxide single crystals

2014 Fiscal Year Final Research Report

• Project/Area Number: 24560800
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical properties of metals
• Research Institution: Yokohama National University
• Principal Investigator: SEKIYA takao 横浜国立大学, 工学(系)研究科(研究院), 教授 (60211322)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 光誘起永続物性 / 輻射緩和 / 二酸化チタン / 不純物ドーピング / 光誘起キャリア

Outline of Final Research Achievements

In UV-irradiated EPR spectra of Al-doped anatase titanium dioxide single crystal, EPR sextuplet due to a hyper fine splitting (hfs) interacting with nuclear spin of doped Al, is observed at temperatures below 80 K. The UV-induced EPR sextuplet signal can be persistently observed in the dark below 80 K. An optical emission due to the recombination of UV-generated and persistently trapped carriers can be observed at around 2.05 eV, when the sample crystal irradiated UV light below 80 K is heated in the dark. In photoluminescence measurement, a broad band is observed at around 2.25 eV. The difference between photoluminescence and emission by persistently trapped carrier recombination is mainly caused by impurity level formed by doped Al. In Nb-doped anatase titanium dioxide single crystal, little change induced by UV-irradiation is observed on optical absorption, EPR spectra and electric conductivity. This indicates UV-induced absence of persistently trapped carriers in Nb-doped crystal.

Free Research Field

材料科学・光物性