Point defects in C-doped α-Al2O3 crystals

A. Shmilevich, R. Chen, D. Weiss, N. Kristianpoller

Research output: Contribution to journalArticlepeer-review

Abstract

Luminescence methods were applied for the study of point defects in α-Al2O3:C crystals. Thermoluminescence (TL), optically stimulated luminescence (OSL) and phototransferred thermoluminescence (PTTL) as well as X-luminescence (XL) were measured. Results were compared to those obtained in nominally pure samples. The main TL and PTTL peaks appeared in the C-doped samples at the same temperatures and with the same thermal activation energies as in the pure α-Al2O3 crystals, indicating that they are due to the same traps. Some notable differences were, however, observed in the emission spectra of the C-doped and the pure samples. The TL emission of the 260K peak in the Al2O3:C crystals showed main bands at 310 and 330nm; and weaker bands at 410 and near 520nm. At the 280K and the higher temperature peaks the 330 and 410nm bands became stronger. The 330 and 410nm bands also appeared in the PTTL, OSL and XL emission spectra of the doped samples. In the pure crystals only a 310mn band was recorded at low temperatures. Above 280K a weak broad band appeared near 325nm; this band could be resolved into two components at 310 and 330nm, which are attributed to two different processes. The 330 and 410nm bands have been ascribed to F+ and F-center emissions respectively. This is supported by the measurements of the excitation spectra of the 330 and 410nm OSL emission bands which showed maxima at wavelengths that coincide with the F+ and F absorption bands. The present results also fit previous conclusions regarding the relatively high F+ concentration in the C-doped Al2O3 crystals. An emission near 520nm has previously been ascribed to an interstitial Ali+ ion. The 310nm band which appeared in the same cases as the weaker 520nm band may also be due to an interstitial Ali+ ion.

Original languageEnglish
Pages (from-to)65-68
Number of pages4
JournalMaterials Science Forum
Volume239-241
StatePublished - 1997

Keywords

  • AlO:C
  • Luminescence
  • Point Defects

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