Radiation Measurements 42 (2007) 882 – 886
www.elsevier.com/locate/radmeas
Luminescence of Bi
3+
ions in Y
3
Al
5
O
12
: Bi single crystalline films
Yu. Zorenko
a , ∗
, V. Gorbenko
a
, T. Voznyak
a
, V. Vistovsky
a
, S. Nedilko
b
, M. Nikl
c
a
Laboratory of Optoelectronic materials (LOM), Ivan Franko National University of Lviv, 79017 Lviv, Ukraine
b
Physical Faculty of Kyiv National Taras Shevchenko University, 03680 Kyiv, Ukraine
c
Institute of Physics AS CR, Cukrovarnicka 10, 162 53 Prague, Czech Republic
Received 20 December 2006; accepted 1 February 2007
Abstract
The absorption and cathodoluminescence spectra of single crystalline films (SCF) of Y
3
Al
5
O
12
: Bi garnet depending on Bi concentration
were analyzed. For consideration of the nature of the UV and visible Bi-related emission bands the time-resolved luminescence of Bi
3+
(ns
2
)
ions in YAG:Bi SCF was studied at 10K under excitation by synchrotron radiation. The difference in the excitation spectra and emission decay
of the UV and visible bands has been explained via radiative relaxation from the
3
P
1,0
excited states to the
1
S
0
ground state of the isolated
and pair/clustered Bi
3+
emission centers in the garnet lattice, respectively.
© 2007 Elsevier Ltd. All rights reserved.
Keywords: Bi
3+
ions luminescence; Liquid phase epitaxy; Single crystalline films
1. Introduction
Y
3
Al
5
O
12
:Bi (YAG:Bi) single crystalline films (SGF) ob-
tained by liquid phase epitaxy (LPE) were proposed for the use
as tunable cathodoluminescent screens with the Bi
3+
-related
emission bands in the UV and blue spectral ranges (Volzenskaja
et al., 1988). Meanwhile, YAG:Bi SCF are also useful model
objects for study of the Bi
3+
luminescence in the garnets com-
pounds. However, to our knowledge, the investigation of the
Bi
3+
emission in the YAG single crystalline host has not been
performed till now. This is mainly caused by large evapora-
tion rates of Bi
2
O
3
oxide during the YAG crystal growth from
melt at 1930
◦
C which prevents obtaining samples with suit-
able Bi content. Unlike the synthesis from melt the LPE allows
to dope SCF of oxides with volatile compounds of ns
2
–ions
(Pb
2+
, Bi
3+
) directly during the SCF growth in the wide con-
centration range (up to a few at%) which are sufficient for ob-
taining high light yield (LY) of SCF under e-beam or -particle
excitation (Zorenko et al., 2000).
Recently, the luminescence of the Bi
3+
ions in the
Gd
3
Ga
5
O
12
(GGG) (Ilmer et al., 1994); Lu
3
Al
5
O
12
(LuAG),
∗
Corresponding author.
E-mail address: zorenko@electronics.wups.lviv.ua (Yu. Zorenko).
1350-4487/$ - see front matter © 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.radmeas.2007.02.030
Y
3
Ga
5
O
12
(YGG) and YAG (Setlur and Srivastava, 2006) gar-
nets host has been studied in powder samples obtained by
solid-state synthesis and YGG single crystals grown by micro-
pulling-down method (Nikl et al., 2005). The structure of photo-
luminescence and excitation spectra, as well as the decay ki-
netics in the UV and visible (VIS) ranges was reported and
analyzed in these works. At the same time, certain ambiguities
in interpretation of the nature of the Bi-related UV and VIS
emission bands in the mentioned papers stimulate us to inves-
tigate in detail the Bi
3+
luminescence in Bi-doped SCF in the
wider (0.2–2 at%) concentration range.
In this paper, we present the results of investigation of the
absorption and cathodoluminescence (CL) of YAG:Bi SCF de-
pending on the concentration of Bi
3+
ions, as well as the time-
resolved luminescence of Bi
3+
in YAG:Bi SCF at 10K under
excitation by synchrotron radiation (SR).
2. Experimental results
The YAG:Bi SCF with a thickness of 15.35 m was grown
in LOM (Lviv University) by LPE from melt-solution based on
Bi
2
O
3
oxide flux on the YAG substrates. The concentration of
Bi
3+
ions in the SCF varied as 1/T
g
function, where T
g
is the
growth temperature in the 910–965
◦
C range. The content of