Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase
The work has suggested an adequate model describing formation of defects in films of AIVBVI compounds in vapor-phase growth. Being based on this model, it has given an analytical description of dependences for film electrophysical parameters (concentrations n, p and mobilities µn, µp of free char...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2008
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| Zitieren: | Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase / Ya.P. Saliy, І.М. Freik, V.V. Prokopiv (Jr) // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 2. — С. 167-170. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-1188502017-06-01T03:06:59Z Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase Saliy, Ya.P. Freik, I.M. Prokopiv (Jr), V.V. The work has suggested an adequate model describing formation of defects in films of AIVBVI compounds in vapor-phase growth. Being based on this model, it has given an analytical description of dependences for film electrophysical parameters (concentrations n, p and mobilities µn, µp of free charge carriers) on technological factors of film growth. We have calculated concentrations of activated and inactivated defects as subject to temperature of film deposition. The developed model enables determination of entropy and enthalpy of defect formation processes. 2008 Article Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase / Ya.P. Saliy, І.М. Freik, V.V. Prokopiv (Jr) // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 2. — С. 167-170. — Бібліогр.: 6 назв. — англ. 1560-8034 PACS 71.20.Nr, 71.55.-i, 81.15.Aa http://dspace.nbuv.gov.ua/handle/123456789/118850 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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English |
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The work has suggested an adequate model describing formation of defects in
films of AIVBVI compounds in vapor-phase growth. Being based on this model, it has
given an analytical description of dependences for film electrophysical parameters
(concentrations n, p and mobilities µn, µp of free charge carriers) on technological factors
of film growth. We have calculated concentrations of activated and inactivated defects as
subject to temperature of film deposition. The developed model enables determination of
entropy and enthalpy of defect formation processes. |
| format |
Article |
| author |
Saliy, Ya.P. Freik, I.M. Prokopiv (Jr), V.V. |
| spellingShingle |
Saliy, Ya.P. Freik, I.M. Prokopiv (Jr), V.V. Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Saliy, Ya.P. Freik, I.M. Prokopiv (Jr), V.V. |
| author_sort |
Saliy, Ya.P. |
| title |
Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase |
| title_short |
Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase |
| title_full |
Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase |
| title_fullStr |
Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase |
| title_full_unstemmed |
Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase |
| title_sort |
formation and activation of defects in films of aivbvi compounds in the process of growing from vapor phase |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2008 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/118850 |
| citation_txt |
Formation and activation of defects in films of AIVBVI compounds in the process of growing from vapor phase / Ya.P. Saliy, І.М. Freik, V.V. Prokopiv (Jr) // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 2. — С. 167-170. — Бібліогр.: 6 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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| first_indexed |
2025-07-08T14:46:44Z |
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2025-07-08T14:46:44Z |
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| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 3. P. 167-170.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
167
PACS 71.20.Nr, 71.55.-i, 81.15.Aa
Formation and activation of defects in films of AIVBVI compounds
in the process of growing from vapor phase
Ya.P. Saliy, І.М. Freik, V.V. Prokopiv (Jr)
Vasyl Stefanyk Precarpathian National University
57, Shevchenko str., 76000 Ivano-Frankivsk, Ukraine
Phone: +380(342) 50-37-52; e-mail: prk@tvnet.if.ua
Abstract. The work has suggested an adequate model describing formation of defects in
films of AIVBVI compounds in vapor-phase growth. Being based on this model, it has
given an analytical description of dependences for film electrophysical parameters
(concentrations n, p and mobilities µn, µp of free charge carriers) on technological factors
of film growth. We have calculated concentrations of activated and inactivated defects as
subject to temperature of film deposition. The developed model enables determination of
entropy and enthalpy of defect formation processes.
Keywords: defects, thin film, AIVBVI compounds, film growth.
Manuscript received 28.02.08; revised manuscript received 25.03.08; accepted for
publication 15.05.08; published online 30.06.08.
1. Introduction
Semiconductor films of AIVBVI components contain
various structural defects affecting considerably their
electrophysical behavior. The principal technological
parameters determining the structural perfection, level of
deviation from stoichiometry of films grown using
different methods from the vapor phase are temperatures
of deposition and evaporation, partial pressures of
vapors of chalcogen and metal in the condensation zone
and also during immediate deposition [1].
Ascertaining the nature and behavior of various
structural defects is a necessary condition for scientific
management of structurally sensitive properties and
processes.
2. Experiment and calculations
Most of defects formed in the course of film growth by
deposition are thermodynamically unstable, and a system
in this case comes into imbalance. Equilibrium can be
obtained by various means and, as a rule, is realized by a
range of meta-steady states. The defects of one type while
interacting can annihilate or create defects of other types.
Often quasi-chemical reactions with predetermined
enthalpies are used for supporting technological
dependences. Thus, a balance of point atomic defects of
a compound MN and molecules of vaporized metal M or
chalcogen N at a temperature of film deposition TS is
described, for instance, using the following quasi-
chemical reactions and correlations for concentrations
and pressures:
i
V MM → , ( ) [ ] MiS PMTK /1 = , (1)
MN
V VNN +→22/1 , ( ) [ ] 2/1
2 /
iNMS PVTK = , (2)
( )Siii kTHKK /exp0 ∆−=
is an equilibrium constant, аnd iH∆ is enthalpy of the
i-th quasi-chemical reaction.
An evaporation of the material MN at the
evaporator's temperature TE occurs with dissociation:
VVS NMMN 22/1+→ , ( ) 2/1
3 /
iNME PPTK = . (3)
Solution of the equation set (1)–(3) produces
dependences of defect concentration on temperature of
deposition and evaporation:
[ ] [ ] ( )Sii kTHMM /exp 1∆−= ∞ , (4)
[ ] [ ] ( )SMM kTHVV /exp 2∆−= ∞ , (5)
[ ] ( )EMi TPKM 0
1=∞ , [ ] ( )ENM TPKV
i
2/10
2=∞ .
These dependences are linearized in coordinates of
logarithm of concentration inversely proportional to
temperature, i.e. depending on the enthalpy sign they
must have areas of swift rise at decreasing or increasing
temperatures.
It should be mentioned that if a concentration of
one type of defects outnumbers and exceeds the intrinsic
concentration of charge carriers ni, a concentration of
free charge carriers n equals a concentration of
outnumbering defects.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 3. P. 167-170.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
168
Table 1. Parameters of approximation of technological dependences of concentration Ni0, ∆Si, ∆Hi and mobility ∆µi0, ∆Si,
∆Hi, µph of free charge carriers in MN.
No. Compound N10, 1018 сm–3;
1/µ10, (V·s)/m2 ∆S1 ∆H1, еV N20, 1018 сm–3;
1/µ20, (V·s)/m2 ∆S2 ∆H2, еV 1/µ ph,
(V·s)/m2
1.9 ± 0.1 –18 ± 2 –0.81 ± 0.09 0.97 ± 0.07 43 ± 3 2.1 ± 0.1 1 PbSe
1.9 ± 0.1 –17 ± 1 –0.72 ± 0.03 0.74 ± 0.02 34 ± 2 1.9 ± 0.1 0.30 ± 0.02
2.0 ± 0.1 –25 ± 2 –1.20 ± 0.09 0.54 ± 0.07 37 ± 1 1.9 ± 0.1 2 PbSe0.8Te0.2 14.0 ± 0.8 –29 ± 1 –1.15 ± 0.06 100 ± 2 35 ± 8 2.0 ± 0.5 0.70 ± 0.04
0.20 ± 0.02 –15 ± 1 –0.77 ± 0.04 3 PbTe
2.1 ± 0.1 –33 ± 1 –1.31 ± 0.05 0.17 ± 0.02 38 ± 6 2.0 ± 0.3 0.28 ± 0.02
5.0 ± 0.2 –19 ± 3 –0.9 ± 0.1 4 (SnTe)0.2(PbSe)0.8 8.6 ± 0.2 –23 ± 1 –0.97 ± 0.06
1.52 ± 0.02 –18 ± 1 –0.89 ± 0.06 5 Pb0.8Sn0.2Te
4.1 ± 0.1 –20 ± 3 –0.8 ± 0.1 43 ± 1 15 ± 3 1.0 ± 0.1 0.23 ± 0.02
130 ± 5 –40 ± 6 –2.1 ± 0.2 180 ± 10 20 ± 2 0.9 ± 0.1 6 SnTe
8.8 ± 0.1 –40 ± 10 –2.0 ± 0.5 5.5 ± 0.5 12 ± 2 0.5 ± 0.1 0.018 ± 0.002
Let us examine experimental dependences of
concentration and mobility of free charge carriers upon
the temperature of films deposition for lead and tin
chalcogenides (Figure) [1]. The films are categorized
into two groups: Group 1 contains lead salts and Group 2
contains solid solutions of lead and tin salts. On
experimental dependences 1 and 2 of Group 1 both at
low (ТS < 530 К) and at high (ТS > 580 К) deposition
temperatures, the changes of concentration of free
charge carriers to the temperature are slight, whereas in
the inversion area they are great. It should be noted that
after the inversion a dependence of the hole
concentration is sharper than the electron concentration
before inversion. On other dependences, we also note
slow changes.
A decreasing concentration of electrons in films of
lead chalcogenides can be explained by a decreasing
concentration of donors, for example vacancies of
chalcogen or interstitial atoms of lead, an increasing
concentration of holes can be attributed to an increase of
vacancies of chalcogen. We attribute a change in the
hole concentration in solid solutions to a change in the
concentration of acceptors which are vacancies of tin as
well as chalcogen [2].
Thus, on experimental dependences both at low and
high temperatures of deposition we observe areas of
weak dependence of the concentration and mobility of
free charge carriers upon temperature. To describe these
dependences, we work out a function for a concentration
of defects that is similar to a previous one but has areas
of slight change or saturation:
[ ] [ ] ( )( )Sii kTHSMM /exp1/ 110 ∆+∆−+= , (6)
[ ] [ ] ( )( )SMM kTHSVV /exp1/ 220 ∆+∆−+= . (7)
Let us present a model that grounds such
tendencies. During the growth an unstable system of
defects is formed. It can be an indigested solution of
point defects which are activated or deactivated during
relaxation of crystal structure. To activated states
(centers), we shall attribute defects that can be revealed
by electrophysical methods. Thus, an excessive
component can generate crystal point defects of different
types, saturation or new phases on surface or volume
(precipitates), etc.
Let us assume that N0 is the concentration of
defects formed during a period of evaporation with
deposition material, for instance, a superstoichometric
concentration of one of the components, where a part of
defects is activated by the concentration Na and another
part remains inactivated by the concentration aN , thus
aa NNN +=0 . (8)
Transmission from one state to another in this
system occurs with a change of entropy and enthalpy. A
necessity of an evident accounting for change of entropy
∆S in calculations of equilibrium concentrations of defects
is suggested in [3] and used, for example, in [4, 5].
( )kTHSNN aa /exp ∆−∆= , (9)
then
( )( )kTHSNN a /exp1/0 ∆+∆−+= . (10)
Let us use similar correlations to explain
dependence of mobility on the deposition temperature.
According to Matissen's rule, we add together
reciprocals to mobility µi, related to different scattering
processes
∑
µ
=
µ i i
11
. (11)
Let us examine scattering processes on ionized
defects and phonons phµ . The mobility is connected
with scattering on ionized defects in the inverse ratio to
their concentration µ ~
N
1
. Thus,
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 3. P. 167-170.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
169
Table 2. Constants of equilibrium of reactions of exceeding
atomic defects formation in MN. Pressure is measured in
mm Hg, concentrations in сm–3, enthalpies in еV.
PbSe PbTe SnTe
0
1K (∆H1)
7.03⋅109
(–1.98)
4.03⋅1012
(–1.45)
1.7⋅1018
(–1.61)
0
2K (∆H2)
4.05⋅1018
(0.21)
2.12⋅1018
(0.11)
4.6⋅1018
(0.38)
0
3K (∆H3)
1.05⋅1016
(3.86)
9.15⋅1014
(3.51)
1.9⋅1014
(3.80)
( )( )Siiii kTHS /exp1/0 ∆+∆−+µ=µ . (12)
It is considered that a phonon constituent of
scattering does not depend on the concentration of
defects.
We define adjusting parameters N10, ∆S1, ∆H1, N20,
∆S2, ∆H2 approximating experimental dependences of
concentrations of free charge carriers on the temperature
of condensation n(TS), and parameters
10
1
µ
, ∆S1, ∆H1,
20
1
µ
, ∆S2, ∆H2,
ph
1
µ
approximating experimental
dependences of mobilities µ(TS). Let us consider the
hypothesis that the values of the pairs of adjusting
parameters ∆S1, ∆H1 and ∆S2, ∆H2 are close to the
concentration as well as to the mobility in groups of lead
chalcogenides and solid solutions of lead and tin
chalcogenides displayed in Table 1. We see that for most
of components the increases in entropy and enthalpy
calculated by the concentration and mobility are
practically similar. By values, the calculated increases in
enthalpies differ approximately twofold from those used
in [6] (Table 2). The table shows that at defined
pressures of chalcogen and metal in a vapor-phase with a
change of the deposition temperature the concentration
of vacancies of metal increases slightly, and that of
interstitial atoms decreases abruptly, it is shown by
minus-plus signs and values of enthalpies changes.
For a part of the processes of activation in Table 1,
both entropy and enthalpy decrease (a change of these
values is negative), i.e. the atoms turn into a crystal
(main position) solid phase from an amorphous
(interstitial position) phase, for another part both entropy
and enthalpy increase (a change of these values is
positive), i.e. the atoms of metal of a crystal phase turn
into a vapor phase.
Dependences of the concentration and mobility of charge carriers on temperature at 77 К in AIVBVI films, TE = 820 К, numbers
at the curves correspond to numbers of compounds in Table 1. For films 1, 2, a transition from n- to p-type takes place at the
increase of temperature; films 3 – n-type; 4, 5 and 6 – p-type of conductivity. The dotted lines denote concentrations of defects
if films contain both types.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 3. P. 167-170.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
170
3. Summary
The work has suggested a model of formation and
activation of point defects in films of AIVBVI compounds
in vapor-phase growth, which sufficiently explains
temperature dependences of the concentration and
mobility of free charge carriers for six analyzed
substances.
Enthalpies for reactions of formation and activation
of point defects were found.
References
1. D.M. Freik, М.А. Galushchak, L.I. Mezhilovska,
Physics and Technology of Semiconductor Films.
Vyshcha Shkola, Lviv, 1988, p. 152 (in Ukrainian).
2. D.М. Zayachuk, V.А. Shenderovskiy, Intrinsic
defects and electronic processes in АIVBVI // Ukr.
fiz. zhurnal 36(11), p. 1692-1712 (1991) (in
Ukrainian).
3. B.F. Ormont, Introduction to Physical Chemistry
and Crystal Chemistry of Semiconductors.
Vysshaya Shkola, Moscow, 1982, p. 528 (in
Russian).
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М.B. Kotlyarevskiy, Е.P. Potapenko // Opto-
elektronika i poluprovodnikovaya tekhnika
(Naukova dumka, Kyiv) 37, p. 91–98 (2002) (in
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dynamics of point defects in cadmium telluride //
Fizyka i khimiya tverd. tila (Ivano-Frankivsk) 6(3),
p. 493-497 (2005) (in Ukrainian).
6. V.P. Zlomanov, А.М. Gas’kov, Intrinsic and
impurity defects in AIVBVI compounds, In: Growth
of Semiconductor Crystals and Films, Part 2.
Nauka, Siberian Branch, Novosibirsk, 1984,
p. 116-133.
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