The luminescence of sapphire subjected to the irradiation of energetic hydrogen and helium ions

Abstract

The luminescence of during and irradiation was measured in the 190 - 820 nm wavelength range. The luminescence evolution with the ion fluence exhibits two behaviours : (i) at low fluence, the amount of centres increases; (ii) at high fluences, these defects are completely (F centres) or partially ( centres) annihilated. This phenomenon results from two concomittant mechanisms : a conversion between F and defects and a destruction of both luminescent species resulting from the radiation-induced damage. By using a simple model we have determined the cross sections associated with creation and annihilation of the centres. The irradiated samples were also investigated by cathodoluminescence and Auger electron spectroscopy. A higher concentration of structural defects and centres is evidenced at the sample area previously irradiated by ions, leading to an unsteady regime of the surface potential under electron excitation.

Ionoluminescence in the Helium Ion Microscope

“…Therefore, even though some luminescence of the sapphire was detected under the ion beam, it is many orders of magnitude lower than that under the electron beam from the GaN in this sample. Luminescence of sapphire, excited via electrons (CL) (Miyauchi & Shibata, 1993) or He ions (IL) (Jardin et al, 1996), has been studied previously. Jardin et al have reported strong IL emission of a sapphire sample when irradiated with a 2 MeV He + beam (Jardin et al, 1996).…”

“…Luminescence of sapphire, excited via electrons (CL) (Miyauchi & Shibata, 1993) or He ions (IL) (Jardin et al, 1996), has been studied previously. Jardin et al have reported strong IL emission of a sapphire sample when irradiated with a 2 MeV He + beam (Jardin et al, 1996). The IL intensity initially increases with increasing ion dose due to creation of defects that act as F + centres.…”

Material characterization and modification using helium lon microscopy : various examples

“…As expected it exhibits luminescence around 415 nm. However, the by far strongest peak at 330 nm corresponds to the emission of F + -centers [164,165]. An F -center in sapphire (Al 2 O 3 ) consists of two electrons, which occupy an oxygen vacancy.…”

“…An F -center in sapphire (Al 2 O 3 ) consists of two electrons, which occupy an oxygen vacancy. Under irradiation an F-center can lose an electron and is converted into an F + -center [164,165]. A small sharp peak at ∼695 nm originates from the impurity Cr 3+ ions [165,166].…”

“…Under irradiation an F-center can lose an electron and is converted into an F + -center [164,165]. A small sharp peak at ∼695 nm originates from the impurity Cr 3+ ions [165,166]. The band at 660 nm is a superposition of the Cr 3+ N-lines and sidebands [166,167] opaque for 330 nm light, but transparent for the Cr 3+ associated emission.…”