Physics/7.Optics
Bykov A.M., Lapaeva
S.N., Bykov M.A.
Physical Department of
4 Vernadsky av., Simferopol , Crimea 95007, Ukrain
Research thin films
on the basis of amorphous hydrogenerated silicon
x-ray radiation.
Interest to films amorphous hydrogenerated silicon (a-Si:H) is connected
first of all to an opportunity of application in photoreception devices, and as
for designing such devices, as solar elements, diodes Shottki,
etc. For detailed researches of internal structure films, and introduced in
structure passivation atoms of hydrogen the
information on a degree of disorder of an arrangement of atoms of silicon is
necessary for formation of connections Si-H.
The purpose of the given work is theoretical and
an experimental research of “a degree
of amorphy” films a-Si:H, received a method magnetron dispersions with use of
an ionic source with the help of x-ray radiation.
Let's consider the circuit of research of thin-film
structure on the basis of amorphous hydrogenerated silicon resulted on fig.1.
Let on a
researched film the flat wave of individual amplitude falls. Then on the screen
1 the wave with complex amplitude will be fixed:
a(ξ,η)
~T1(ξ,η)+T2(ξ,η)exp(-2πiηC0)
where T1(ξ,η)
– Fourier an image of function of passage t1(x,y)
beam through a film on a basis a-Si:H; T2(ξ,η) - fourier an image of function t2(x,y+C0)
the system forming basic beam; ξ,η - spatial
frequencies, Ñ0 - a constant arising as a result of
shift on an axis y of a basic beam concerning a beam, last a film.
In view of that wave fronts, diffract on atoms of
silicon and passivate hydrogen are spatially shattered,
function T1
(ξ,η) can be submitted as:
T1(ξ,η)=
Tk (ξ,η) (1)
where N – quantity of wave fronts, diffract on atoms of a film a-Si:H.
On the screen 1 the wave with complex
amplitude will be fixed::
a(ξ,η)
~
Tk(ξ,η)+T2(ξ,η)exp(-2πiηC0) (2)
Transmission the
screen 1 it will be proportional to intensity of radiation:
t~
TkTj+T2T2*+
T2T2*exp(2πiηC0)
T2*T2
exp(-2πiηC0) (3)
Let's consider last composed (3). In view of that Fourier - the converter 2 carries out the
opposite Fourier -
transformation, the complex amplitude of a wave on the screen 2 looks like:
a(x,y) ~F-1{
TkTj*T2exp(-2πiηC0)}, (4)
where a symbol F-1 return
transformation Fourier is
designated. After transformations of expressions (4) it is resulted in a kind:
a(x,y) ~
[tk(x,y)♥ tj(x,y)]
t2(õ,ó+Ñ0) (5)
where ♥ - operation of correlation, - operation of
convolution.
If to each
atom of a film to put in conformity σ - function of Diraka,
correlation function in expression (5) is represented, how
[tK(x,y) ♥ tj(x,y)]= 
This
expression is distinct from zero only in that case when k=j; hence in (5)
summation on k it is removed, and it can be written down as:
a(x’,y’) ~ [tk(x,y)
♥ tj(x,y)]t2(õ,ó+Ñ0) (6)
From
expression (6) follows, that if passing
systems in a plane of the screen 2 it is chosen in such a manner that
autocorrelation function in expression (6) had a sharp central maximum (that
corresponds completely to a stochastic arrangement of atoms of a film a-Si:H) in a target plane õ’,ó’ at ’ the
screen 2 the phasa-homogeneous front will be generated.
Thus, presence of phasa-homogeneous x-ray front unequivocally
testifies about hundredchaotic an arrangement of atoms of a film a-Si:H.
The method of the Fourier-analysis of x-ray
radiation shows a stochastic arrangement of atoms thin films on a basis a-Si:H, received by a method
magnetron dispersions with use of an ionic source.
References
1.
Frank F.R.,
Faller A. H. High-Temperature
CVD for Crystalline-Silicon Thin-Film Solar Cells// IEEE Tranctions
on Electron Devices.-1999.- Vol. 46, No. 10 (October).-p.2048-2054.
2.
Golikova O.A., Kazanin M.M. Features of electronic properties and
structures of films a-Si:H with a heightened
photosensitivity // Physics and Technics of
Semiconductors. - 1999. - ¹3 -Ñ.336-339.
3.
Bykov A.M., Voljar
A.V. Opt. and Spectr. 1984, v56, #5, p.894-899
1.
Bykov A.M., Voljar
A.V. Ukr. Phys. J. 1979, v24, #1, p.132-134