Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes
The relaxation dynamics of the exciton resonances in the layer InxTl1−xI semiconductor for its transition from bulk crystals to the quantum-size nanocrystals synthesised within the different matrices is analysed. The mordenitetype (Na-MOR)Na₈[Al₈Si₄₀O₉₆]⋅24H₂O zeolite, beryl and porous silicon...
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| Дата: | 2008 |
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Інститут металофізики ім. Г.В. Курдюмова НАН України
2008
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| Цитувати: | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes / A.V. Franiv, O.V. Bovgyra, O.V. Franiv, D.B. Goyer // Наносистеми, наноматеріали, нанотехнології: Зб. наук. пр. — К.: РВВ ІМФ, 2008. — Т. 6, № 1. — С. 75-81. — Бібліогр.: 5 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859618125955203072 |
|---|---|
| author | Franiv, A.V. Bovgyra, O.V. Franiv, O.V. Goyer, D.B. |
| author_facet | Franiv, A.V. Bovgyra, O.V. Franiv, O.V. Goyer, D.B. |
| citation_txt | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes / A.V. Franiv, O.V. Bovgyra, O.V. Franiv, D.B. Goyer // Наносистеми, наноматеріали, нанотехнології: Зб. наук. пр. — К.: РВВ ІМФ, 2008. — Т. 6, № 1. — С. 75-81. — Бібліогр.: 5 назв. — англ. |
| collection | DSpace DC |
| container_title | Наносистеми, наноматеріали, нанотехнології |
| description | The relaxation dynamics of the exciton resonances in the layer InxTl1−xI semiconductor
for its transition from bulk crystals to the quantum-size nanocrystals
synthesised within the different matrices is analysed. The mordenitetype
(Na-MOR)Na₈[Al₈Si₄₀O₉₆]⋅24H₂O zeolite, beryl and porous silicon are
used as matrices. As experimentally shown, the size-effects’ influence affect
the parameters of the band-to-band transitions and the genesis of exciton
states in substitutional solid solution of InxTl1−xI.
На прикладі шаруватого напівпровідника InxTl1−xI проаналізовано динаміку релаксації екситонних збуджень при переході від блочних монокристалів до нанокристалів, синтезованих у ріжних матрицях, таких як поруватий кремній, берил та природній цеоліт Na₈[Al₈Si₄₀O₉₆]⋅24H₂O (морденіт). Експериментально виявлено вплив розмірного квантування на параметри зона-зонних переходів, а також генезис екситонних станів твердих розчинів заміщення InxTl1−xI.
На примере слоистого полупроводника InxTl1−xI проанализирована динамика релаксации экситонных возбуждений при переходе от блочных монокристаллов к нанокристаллам, синтезированным в разных матрицах,
таких как пористый кремний, берилл и цеолит Na₈[Al₈Si₄₀O₉₆]⋅24H₂O
(морденит). Экспериментально выявлено влияние размерного квантовния на параметры зона-зонных переходов, а также генезис экситонных
состояний твердых растворов замещения InxTl1−xI.
|
| first_indexed | 2025-11-28T23:37:38Z |
| format | Article |
| fulltext |
75
PACS numbers: 71.35.Cc, 73.20.Mf, 77.84.Bw, 78.55.-m, 78.67.Bf, 81.40.Tv
Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric
Matrixes
A. V. Franiv, O. V. Bovgyra, O. V. Franiv*, and D. B. Goyer**
Ivan Franko L’viv National University,
8 Kyryl i Mefodiy Str.,
79005 L’viv, Ukraine
*National University ‘L’vivs’ka Politekhnika’,
12 St. Bandera Str.,
79013 L’viv, Ukraine
**Institute of Electron Physics,
21 Universitets’ka Str.,
88017 Uzhhorod, Ukraine'
The relaxation dynamics of the exciton resonances in the layer InxTl1−xI semi-
conductor for its transition from bulk crystals to the quantum-size nanocrys-
tals synthesised within the different matrices is analysed. The mordenite-
type (Na-MOR) Na8[Al8Si40O96]⋅24H2O zeolite, beryl and porous silicon are
used as matrices. As experimentally shown, the size-effects’ influence affect
the parameters of the band-to-band transitions and the genesis of exciton
states in substitutional solid solution of InxTl1−xI.
На прикладі шаруватого напівпровідника InxTl1−xI проаналізовано дина-
міку релаксації екситонних збуджень при переході від блочних монокри-
сталів до нанокристалів, синтезованих у ріжних матрицях, таких як по-
руватий кремній, берил та природній цеоліт Na8[Al8Si40O96]⋅24H2O (морде-
ніт). Експериментально виявлено вплив розмірного квантування на па-
раметри зона-зонних переходів, а також генезис екситонних станів твер-
дих розчинів заміщення InxTl1−xI.
На примере слоистого полупроводника InxTl1−xI проанализирована дина-
мика релаксации экситонных возбуждений при переходе от блочных мо-
нокристаллов к нанокристаллам, синтезированным в разных матрицах,
таких как пористый кремний, берилл и цеолит Na8[Al8Si40O96]⋅24H2O
(морденит). Экспериментально выявлено влияние размерного квантова-
ния на параметры зона-зонных переходов, а также генезис экситонных
состояний твердых растворов замещения InxTl1−xI.
Key words: substitutional solid solution, indium and thallium iodide, quan-
Наносистеми, наноматеріали, нанотехнології
Nanosystems, Nanomaterials, Nanotechnologies
2008, т. 6, № 1, сс. 75—81
© 2008 ІМФ (Інститут металофізики
ім. Г. В. Курдюмова НАН України)
Надруковано в Україні.
Фотокопіювання дозволено
тільки відповідно до ліцензії
76 A. V. FRANIV, O. V. BOVGYRA, O. V. FRANIV, and D.B. GOYER
tum-size effect, quantum dot.
(Received October 23, 2006)
1. INTRODUCTION
Nowadays the control changing of fundamental characteristics and opti-
cal parameters of semiconductors remains important problem in microe-
lectronics. Special attention devotes to operating of the fundamental and
optical values such as: band gap energy Eg, energy characteristics of the
exciton resonances (exciton band maximum energy, exciton band half-
width) without crystal structure and chemical composition changing.
It is known that this problem may be solved if dimension of semicon-
ductor crystal gradually decrease and bulk crystal transfers into quasi-
zero-dimensional structure of ‘quantum-dot’ type. The reducing of
quantum-dot size leads to dimensional quantization of the free carriers
and causes a high-energy shift of the absorption edge.
In this work, the investigations of optical properties of InxTl1−xI lay-
ered crystals synthesised into different matrices that establish desired
conditions of nanocrystals sizes are reported. The mordenite-type
Na8[Al8Si40O96]⋅24H2O zeolite (Na-MOR), beryl and porous silicon are
used as matrices.
2. MODELS AND FORMULATION
In reference [1], it was shown that for the given case the energy E of
minimum phototransition is described by the following expression:
2 2 3
2
1
1
,
2
b
g ex
i i
Е E E
=
π
= − +
μ α∑h
(1)
where μ is an effective mass of electron and hole,
b
gE –band gap energy
of bulk crystals, exE –exciton binding energy, αi is effective size of the
‘i’-th quantum dot. It is clear that E is a function of the sizes ‘α
−2’, and
the reducing of quantum-dot sizes leads to dimensional quantization of
the free carriers and causes a high-energy shift of the absorption edge.
On the other hand, in the process of the size-dimensional quantiza-
tion, the peculiar dynamics of the exciton states in semiconductor crys-
tal will be revealed. There three different cases may occur: 1–αex > αi,
2–αex ≤ αi, 3–αex << αi, where αex is effective Bohr radius of the free ex-
citon, αi is effective size of nanocrystals,
12 2
2
1 1ex
ex
e h
h n
m me
−
⎛ ⎞ε
α = +⎜ ⎟
⎝ ⎠
.
LUMINESCENCE OF InxTl1−xI NANOCRYSTALS EMBEDDED IN DIELECTRICS 77
The values of αi are equal to one of the unit cell parameters, a, b, c, of
crystal lattice.
In the first case (αex > αi), where spatial distribution of the effective
mass of quasi-particle exceeds the bounds of nanocrystals, free exciton
states are absent. Energy of exchange (Coulomb) interaction between
electron and hole will be as follows:
4 2
2 2
1
.
22
ex
ex
ex
e e
Е
μ
= =
ε αεh
(2)
If me = mh, μex =
2
e h e
e h
m m m
m m
=
+
. In conditions of
2 2 23
2
1
1 1
,
2 2i exi
e
=
π
≥
μ ε αα∑h
the high-energy shift of exciton bands should be observed in optical
spectra.
The third case (αex << αi) is the classic bulk crystal, which was consid-
ered in [2]. Now, if believe that, for a real bulk crystal, αi = 106
nm and
αex = 10 nm, then we can neglect the last member in equation (1) and ob-
tain the classic expression for free hydrogen-like exciton (without taking
into account the exciton-zone dispersion).
Consequently, realising on experiment considered three models of
quantum-size structures we can follow for the dynamics of the exciton
states relaxation on the optic spectra in semiconductors.
3. RESULTS AND DISCUSSION
Layer semiconductors of InI and InxTl1−xI substitutional solid solution
(SSS) are considered as promising model materials for the studies of
the problems above. Masses of the effective electron and hole in these
materials are equal, [3], besides it is known that the model of the hy-
drogen-like Wannier exciton is valid for the bulk crystal [4, 5]. Since
Eex
n = 1 = 0.005 eV, αex
n = 1 = 2.7 nm, bulk crystals of InI and InxTl1−xI SSS
are suitable for using as a model objects with αex << αi.
The nanocrystals of indium and thallium iodide combined with SSS
embedded into solid matrices of porous silicon with pore sizes of 1—50
nm are provided with a model for which αex ≤ αi. For third model
(αex << αi), the quantum-size microcrystals were incorporated into the
natural zeolite Na-MOR (Na8[Al8Si40O96]⋅24H2O). The natural mor-
denite has the one-dimensional emptiness with diameter of αi = 0.7—1
nm. InxTl1−xI molecules were embedded into solid matrices by physical
absorption.
The exciton photoluminescence spectra at different temperature are
investigated in InxTl1−xI. The luminescence from the sample was meas-
ured with used the spectral complex SDL-2-1. The Ar-laser with
λ = 0.47—0.51 μm was used for excitation of photoluminescence.
78 A. V. FRANIV, O. V. BOVGYRA, O. V. FRANIV, and D.B. GOYER
Figure 1 shows the photoluminescence spectra of InI crystal. The
line of recombination of free exciton with hνex = 2.0194 eV and line of
localised exciton hνex = 2.0174 eV [6] is easily seen in photolumines-
cence spectrum of the bulk InI (a). Obtained results are in a good agree-
ment with corresponding parameters of the exciton given in [4, 5].
Photoluminescence spectra for indium iodide incorporated into porous
silicon are shown in Fig. 1, b, b′.
The violet shift of exciton photoluminescence is observed. Consider-
ing the value of the violet shift and regular parameters, αex, Eex
n = 1, μex,
the effective size αi of quantum dot of InI embedded into porous silicon
were calculated (Table 1).
Fig. 1. The photoluminescence spectra of InI crystals: a–bulk crystals; b–
nanocrystals incorporated into porous silicon (αi = 0.01 μm), b′–nanocrystals
incorporated into glass cavities (αi = 0.001 μm), c–nanocrystals incorporated
into natural zeolite Na-MOR (αi = 1 nm).
TABLE 1. Effective sizes of quantum dots in InI.
Crystal αi
experiment, μm αi
experiment/αi
theory
InI (b) 0.5 7
InI (b′) 0.01 2.5
InI (с) 0.0008 1.1
In0.9Tl0.1I (b) 0.5 10
In0.9Tl0.1I (b′) 0.01 3
In0.9Tl0.1I (с) 0.0015 2.1
In0.4Tl0.6I (b) 0.5 11.5
In0.4Tl0.6I (b′) 0.01 5
In0.4Tl0.6I (с) 0.001 1.4
LUMINESCENCE OF InxTl1−xI NANOCRYSTALS EMBEDDED IN DIELECTRICS 79
The line c in Fig. 1 is experimental photoluminescence spectrum of
indium iodide incorporated in solid matrices of natural zeolite Na-MOR
type. Weak band with energy hνex = 2.189 eV are observed. Moreover,
the band half-width is less than free-exciton photoluminescence band-
width in two previous spectra. The temperature decay occurs at T = 35 K
that suits the model of localised exciton well. The absence of the free-
exciton band on photoluminescence spectra completely satisfies the con-
Fig. 2. The exciton photoluminescence spectra of In0.4Tl0.6I crystals: a–bulk
crystals; b–nanocrystals incorporated into porous silicon (αi = 0.05 μm), b′–
nanocrystals incorporated into glass cavities (αi = 0.001 μm), c–nanocrystals
incorporated into natural zeolite Na-MOR (αi = 1 nm).
Fig. 3. The exciton photoluminescence spectra of In0.9Tl0.1I crystals: a–bulk
crystals, b–nanocrystals incorporated into porous silicon (αi = 0.05 μm), b′–
nanocrystals incorporated into glass cavities (αi = 0.001 μm), c–nanocrystals
incorporated into natural zeolite Na-MOR (αi = 1 nm).
80 A. V. FRANIV, O. V. BOVGYRA, O. V. FRANIV, and D.B. GOYER
dition of αex << αi.
The analogous experimental results (Figs. 2, 3) were obtained for
InxTl1−xI SSS. In substitutional solid solution, due to the regular fluc-
tuations of a crystal lattice, the structure of localised-exciton band dis-
plays more distinct than in binary compounds.
The accuracy of band gap energy and binding energy of exciton de-
termination decreases owing to structural disorder. This cause is an in-
accuracy in evaluation of effective size αi of nanocrystals. From experi-
mental results, the dependence of high-energy shift value on the ratio of
nanocrystals’ size to effective Bohr radius of the free exciton was ob-
tained (Fig. 4).
As seen from Fig. 4, the relative parameter of ground exciton state
high-energy shift depends exponentially against the αi/αex ratio.
Moreover, strong quantum dimensional effect of exciton states ap-
pears within the range of 1 ≥ αі/αex ≥ 4. Taking into account small val-
ues of exciton binding energy in InI (RY ≈ 4.3 meV) and relatively small
value of effective Bohr radius (αex ≈ 45 Å), we can conclude that strong
quantum dimensional effect in indium iodide takes place in a region
where sizes of nanocrystals are comparable with lattice parameters.
4. CONCLUSIONS
Decrease of size of the semiconductor InxTl1−xI crystals leads to size quan-
Fig. 4. The high-energy shift of exciton band as a function of ratio of
nanocrystals’ size to effective Bohr radius of the free exciton.
LUMINESCENCE OF InxTl1−xI NANOCRYSTALS EMBEDDED IN DIELECTRICS 81
tization of the electron spectrum. This manifests in a form of the high-
energy shift of exciton bands in photoluminescence spectra.
Synthesis of the semiconductor nanocrystals embedded into porous
matrices with unknown size of emptiness is one of the experimental
methods to determine an effective size of these microemptinesses.
REFERENCES
1. Al. L. Efros and A. L. Efros, Fiz. Tekhn. Poluprovod., 16, No. 7: 1209 (1982)
(in Russian).
2. A. S. Davydov, Quantum Mechanics (Moscow: Nauka: 1973) (in Russian).
3. P. Puepa et al., Fiz. Tverd. Tela, 31, No. 8: 83 (1989) (in Russian).
4. I. V. Blonsky and A. V. Franiv, Solid State Physics, 28, No. 10: 3136 (1986).
5. A. V. Franiv and A. P. Vaskiv, Phys. Electr., 39: 17 (1989).
|
| id | nasplib_isofts_kiev_ua-123456789-76016 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1816-5230 |
| language | English |
| last_indexed | 2025-11-28T23:37:38Z |
| publishDate | 2008 |
| publisher | Інститут металофізики ім. Г.В. Курдюмова НАН України |
| record_format | dspace |
| spelling | Franiv, A.V. Bovgyra, O.V. Franiv, O.V. Goyer, D.B. 2015-02-07T12:52:35Z 2015-02-07T12:52:35Z 2008 Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes / A.V. Franiv, O.V. Bovgyra, O.V. Franiv, D.B. Goyer // Наносистеми, наноматеріали, нанотехнології: Зб. наук. пр. — К.: РВВ ІМФ, 2008. — Т. 6, № 1. — С. 75-81. — Бібліогр.: 5 назв. — англ. 1816-5230 PACS numbers: 71.35.Cc, 73.20.Mf, 77.84.Bw, 78.55.-m, 78.67.Bf, 81.40.Tv https://nasplib.isofts.kiev.ua/handle/123456789/76016 The relaxation dynamics of the exciton resonances in the layer InxTl1−xI semiconductor for its transition from bulk crystals to the quantum-size nanocrystals synthesised within the different matrices is analysed. The mordenitetype (Na-MOR)Na₈[Al₈Si₄₀O₉₆]⋅24H₂O zeolite, beryl and porous silicon are used as matrices. As experimentally shown, the size-effects’ influence affect the parameters of the band-to-band transitions and the genesis of exciton states in substitutional solid solution of InxTl1−xI. На прикладі шаруватого напівпровідника InxTl1−xI проаналізовано динаміку релаксації екситонних збуджень при переході від блочних монокристалів до нанокристалів, синтезованих у ріжних матрицях, таких як поруватий кремній, берил та природній цеоліт Na₈[Al₈Si₄₀O₉₆]⋅24H₂O (морденіт). Експериментально виявлено вплив розмірного квантування на параметри зона-зонних переходів, а також генезис екситонних станів твердих розчинів заміщення InxTl1−xI. На примере слоистого полупроводника InxTl1−xI проанализирована динамика релаксации экситонных возбуждений при переходе от блочных монокристаллов к нанокристаллам, синтезированным в разных матрицах, таких как пористый кремний, берилл и цеолит Na₈[Al₈Si₄₀O₉₆]⋅24H₂O (морденит). Экспериментально выявлено влияние размерного квантовния на параметры зона-зонных переходов, а также генезис экситонных состояний твердых растворов замещения InxTl1−xI. en Інститут металофізики ім. Г.В. Курдюмова НАН України Наносистеми, наноматеріали, нанотехнології Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes Article published earlier |
| spellingShingle | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes Franiv, A.V. Bovgyra, O.V. Franiv, O.V. Goyer, D.B. |
| title | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes |
| title_full | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes |
| title_fullStr | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes |
| title_full_unstemmed | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes |
| title_short | Luminescence of InxTl1−xI Nanocrystals Embedded in Dielectric Matrixes |
| title_sort | luminescence of inxtl1−xi nanocrystals embedded in dielectric matrixes |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/76016 |
| work_keys_str_mv | AT franivav luminescenceofinxtl1xinanocrystalsembeddedindielectricmatrixes AT bovgyraov luminescenceofinxtl1xinanocrystalsembeddedindielectricmatrixes AT franivov luminescenceofinxtl1xinanocrystalsembeddedindielectricmatrixes AT goyerdb luminescenceofinxtl1xinanocrystalsembeddedindielectricmatrixes |