The exponential increase of the absorption coefficient near the absorption edge is usually explained by existence of the density-of-states tails. Among the quoted theoretical models which are widely used to explain the manifestations of the Urbach rule in semiconductors, are the Sumi–Toyozava and the Dow–Redfield models and ab initio (from begining) theory. Our barrier-cluster-heating model assumes the different creating mechanism of exponential tails. The energy by optical transition is provided to electrons except from photons also from vibration of microregion. It deals about the replenishment of absented photons energy, which is smaller as gap width. Absented energy needed for the transition by light absorption is acumulated in certain microregions of material in the form of vibrational energy. At absorption sufficiently big package of accumulated energy can be used. Energy of emptied microarea is filled by phonons from surrounding of microarea (as result of temperature status of surrounding), resp. phonons of optical background wich are created in given microarea at non radiative recombination of carriers. In this work simplified process at derivating of Urbach rule is listed.

1.
A.
Eucken
,
Ann. Physik
34
,
185
221
, (
1911
).
2.
V. K.
Malinovsky
,
N. V.
Surovtsev
,
Glass Physics and Chemistry
26
,
217
222
(
2000
).
3.
V. K.
Malinovsky
,
N. V.
Surovtsev
,
Chalcogenide Letters
9
,
2
,
79
84
(
2012
).
4.
A.
Heuer
,
R. J.
Silbey
,
Physica B
219–220
,
255
(
1996
).
5.
A.
Heuer
,
R. J.
Silbey
,
Phys. Rev. B
53
,
609
(
1996
).
6.
D. A.
Drabold
,
Journal of Non-Crystalline Solids
266
,
211
(
2000
).
8.
H.
Sumi
,
Y.
Toyoyzawa
,
Phys. Soc. Japan
31
,
342
357
(
1971
).
9.
D.
Dow
,
D.
Redfield
,
APS Journals, Phys. Rev.
5
,
494
610
(
1972
).
10.
I. P.
Studenyak
,
M.
Kranjčec
,
M. V.
Kurik
,
Int. Journ. of Optics and Applic.
4
,
3
,
76
83
(
2014
).
11.
M.
Kranjčec
,
I. P.
Studenyak
,
M. V.
Kurik
,
Journ. of Non-Cryst. Solids
355
,
54
57
(
2009
).
12.
K.
Tanaka
,
K.
Shimakawa
,
Amorphous Chalcogenide Semiconductors and Related Materials
(
Springer
,
2011
), pp.
200
300
.
13.
K.
Tanaka
,
J. Optoelectron. Adv. Mater.
15
,
11–12
,
1165
1178
(
2013
).
14.
M.
Popescu
,
Journ. Optoelectr. Adv. Mater.
7
,
4
,
2189
2210
(
2005
).
15.
I.
Banik
,
Journ. of Optoelectr. and Adv. Materials
14
,
9-10
,
711
716
, (
2012
).
16.
I.
Banik
,
Journal of Non-Crystalline Solids
353
,
1920
1924
(
2007
).
17.
I.
Banik
,
G.
Pavlendová
,
Proc. Thermophysics, Podkylava
2013
,
32
(
2013
).
18.
I.
Banik
,
G.
Pavlendová
,
Trans Tech Publications, Thermophysics and Mass Transfer in Materials Science and Construction
,
Advanced Materials Research
1126
(
2015
).
19.
I.
Banik
,
R.
Banik
, “
Optical absorption, exponential tails and Urbach rule in disordered semiconductors
”, in
Proc. ADEPT 2016
,
High Tatras, Tatranska Lomnica
,
2016
, (in press).
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