Luminescence During Tb-Ion Implantation into Sapphire
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Makoto KUMAGAI* and Masaya IWAKI"* *Saitama University, 255 Simookubo, Urawa-shi, Saitama 338 Japan. "**TheInstitute of Physical and Chemical Research(RIKEN), 2-1 Hirosawa, Wako-shi, Saitama 351-01 Japan.
ABSTRACT A study has been made of the luminescence during Tb-ion implantation in AI20 3 or by Ar- or He-ions bombardment to Tb-ion implanted A420 3. The substrates used were colorless and transparent single crystal ca-A120 3 with (0001) or (1102) surface orientation. Ion implantations of Tb-ions in AI20 3 were carried out at fluences of lxlO13 to IxIO1 7 Tb/cm 2 at 100 keV at nearly room temperature. Change in color of A120 3 substrates by Tb implantation was invisible to the naked eye. The luminescence spectra were measured by Ar (100 keV) or He (50 keV) bombardment to Tb implanted A120 3 or during Tb implantation into A120 3 using a spectroscopy with three optical filters and photomultiplier. The luminescence spectra during Tb implantation into A120 3 have four clear peaks identified as emission due to D-F transitions of TbV3 state. The luminescence spectra of Tb implanted A120 3 excited by He, Ar and Tb bombardment were almost the same except for the luminescence at the wavelength ranging from 300 to 450 nm, which is caused by strong emission from A120 3 itself The peak of the luminescence appears at 550 nm, and its intensity depends on the Tb dose. The maximum intensity of luminescence during Tb implantation at room temperature is obtained as the maximum atomic ratio of implanted Tb is 2-3 atomic %. 1. INTRODUCTION The luminescence had been observed on SiO 2 or CaF 2 by ion bombardment, or y-ray or electron beam excitation, it makes an examination of the relationship between lattice defect and excited states by radiation[l]. The luminescence phenomena also had been observed during the rare earth elements implantation into these insulators. It was found that the color of luminescence is dependent on ion implantation samples and implanted species, and furthermore, its intensity is influenced by the ion dose. We have studied the radiation and doping effects in CaF2, which emitted luminescence during Eu and Tb implantation at 100 keV or Ar bombardment to Eu or Tb implanted CaF212,3]. The optical transmission for all implanted specimens was compatible to that for un-implanted CaF 2 at the level of accuracy of these experiments. The color of luminescence during Eu and Tb implantation into CaF2 depended on the ion species and ion dose; blue due to Eu2 +state at Eu implantation with a low dose level, red due to Eu 3+state at Eu implantation with a high dose level, and green due to Tb3+ state at Tb implantation. We have succeeded white luminescence by double ion implantation of both Eu and Tb ions in CaF2 with control of the dose of Eu and Tb[4]. The mechanism of ion beam induced luminescence of implanted elements, however, is not clear. At these experiments, we have seen the similar luminescence even on an Al target holder. The Al sheet has y-A120 3 in the surface layer so that the luminescence was thought to 147 Mat
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