Achieving epitaxy and intense luminescence in Ge∕Rb-implanted α-quartz

Abstract

The luminescence properties of ion-beam doped silica and quartz depend sensitively on the ion species and fluence and the thermal processing during and after ion implantation. In an attempt to achieve high luminescence intensity and full planar recrystallization of α-quartz, we studied double Ge∕Rb-ion implantation, where the Rb ions serve as a catalyst only. Synthetic α-quartz samples were irradiated with 175 keV Rb ions and subsequently with 120 keV Ge ions with fluences of 1×1014–1×1016ions∕cm2 and postannealed at 1170 K in air. A comparative analysis of the epitaxy, migration of the implanted ions, and cathodoluminescence (CL) were carried out. The CL spectra exhibit three strong emission bands in the blue/violet range at 2.95, 3.25, and 3.53 eV, which were assigned to Rb- and/or Ge-related defect centers. For up to 1015 implanted Geions∕cm2, large fraction (75%) of the Ge atoms reach substitutional Si sites after the epitaxy.

Na-irradiated alpha-quartz: chemical epitaxy and luminescence

“…Their intensities appear correlated in a characteristic way with the Na outdiffusion and epitaxy of the matrix. Bands at the same photon energies and with similar features have also been observed during chemical epitaxy after Rb [10,11] or double Rb/Ge ion implantation [25] and after excimer-laser treatment of Rb-or Cs-doped quartz [5].…”

“…Both energies do not depend on the temperature, but the intensities of the bands do and are thermally quenched with activation energies of 68 and 28 meV, respectively. At 17.5 K, the time constants of 3.6 ns and 1.0 ns are definitely much shorter than the µs time constants of the 2.95 and 3.25-eV CL bands measured in α-quartz by Sahoo et al [25] at room temperature, or the 800-µs time constant of the 2.9/3.7-eV PL doublet found by Pealari et al [22] in silica. A fast PL band centered around 2.7 eV has also been found in SIMOX structures produced by oxygen ion implantation in silicon [23,24] and has been attributed to defects at the interface between Si clusters and the SiO 2 matrix.…”

Shiny quartz: luminescence in ion-implanted and epitaxially recrystallizing α-quartz

“…In all the cases considered, the ion-specific defect centres were found to emit blue-violet CL bands in the 2.9-3.7 eV range. Furthermore, we discuss recent results of high-resolution transmission electron microscopy (TEM) after Ge and Sn implantation [25,26] and Rutherford backscattering channeling spectroscopy (RBS-C) after Ge/Rb implantation [21], which provided first insight into the structure of the luminescent Ge nanoparticles responsible for the blue/violet bands.…”

“…In this work, we discuss CL spectroscopy in correlation with full or partial epitaxy of α-quartz achieved during or after Ge, Ba, alkali (Na, Rb, Cs), or double Rb/Ge-ion implantation [14][15][16][17][18][19][20][21]. When combining the microstructural results on dynamic or chemical epitaxy with the corresponding luminescence data, one may draw conclusions concerning the origin of the CL bands and their relation to the surrounding matrix (crystalline, amorphous, nanoparticles) and the type of photoactive defects.…”

“…For that reason, defect production and annihilation by energetic ion bombardment and thermal annealing is an essential technological issue for understanding the defect dynamics responsible for the optical properties of SiO 2 . Attempts at dynamic, chemical or laser-induced solid phase epitaxial growth of such amorphized layers have been made in order to remove any radiation damage induced during implantation and to achieve high quantum efficiency of the visible cathodoluminescence (CL) light output [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”