World Journal Of Engineering
AB INITIO STUDY OF STRUCTURAL AND ELECTRONIC PROPERTIES OF INN/SI
AND GAN/SI INTERFACES
Mutigullin I.V.1, Abgaryan K.K.1, Bazhanov D.I.2, Stepanyuk O.V.1
1
Institution of Russian Academy of Sciences Dorodnicyn Computing Centre of RAS, Vavilov st.
40, 119333 Moscow, Russia.
2
Faculty of Physics M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow,
Russia.
Introduction
One of the main priorities during the
development of civil and military innovative
radioelectronic defense equipment is the
production of the new semiconductor film
nanostructures based on nitride or oxide
compounds bearing unique physical and
mechanical properties required for solid
state microwave electronics. In this context
very
promising
are
such
nitride
semiconductors as GaN, InN, AlN etc. One
of the most attractive substrates for epitaxial
nitride growth is Si [1]. But due to a large
lattice mismatch between Si(111) substrates
and nitride (0001) surface the interface is
characterized by large strain [2, 3].
In this work we present theoretical
investigation of adhesion properties of
InN(0001)/Si(111) and GaN(0001)/Si(111)
interfaces as well as influence of strain on
band-gap value.
Theory
All the calculations presented in this article
were based on Density functional theory
(DFT)
within
the
local-density
approximation LDA scheme widely used to
study the ground state properties of solids
and their surfaces. [4, 5] DFT LDA
simulations were performed using the
Vienna ab initio simulation package VASP
based on pseudopotentials and a plane-wave
basis set to solve the Kohn–Sham equations
with periodic boundary conditions. [6] To
study the properties of InN/Si and GaN/Si
interfaces, we used a common slab
approximation with a supercell containing
21 atomic layers and a large vacuum space.
All the atomic layers in the slabs were
allowed to relax. The relaxation process was
stopped when the residual force acting on
each atom in the slab was less than 0.01
eV/Å.
Ef
InN
DOS, N states
20
15
10
5
0
-20
-15
-10
-5
0
5
10
15
Energy (eV)
Ef
GaN
DOS, N states
20
15
10
5
0
-20
-15
-10
-5
0
5
10
15
Energy (eV)
Fig. 1. Calculated density of states for bulk
InN and GaN.
Results and Discussion
Both
GaN
and
InN
crystallize
predominantly in wurtzite structure [1].
Calculated bulk lattice constants are in a
good agreement with experimental data [1].
For GaN obtained lattice constant a=3,15 Å
and c/a=1.63 while for InN a=4.50 Å and
c/a=1.62. It is well known that LDA due to
the
so-called
“band-gap
problem”
underestimates the value of bad-gap of
semiconductors [7]. Thus we used LDA+U
[8] to calculate electronic properties of GaN
and InN. In Fig. 1 we demonstrate obtained
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World Journal Of Engineering
electronic densities of states for GaN and
InN. Calculated band-gaps are 3.45 eV and
0.79 eV for GaN and InN respectively,
while experimental values are 3.5 eV [9] and
0.65-0.7 eV [10] respectively.
GaN respectively. In the case of coherent
InN(0001)/Si(111) interface the lattice
mismatch is +9% and our calculations
revealed a strong band-gap decreasing till
0.12 eV.
InN(0001)/Si(111) coherent interface with
Si lattice constant (5,40 Å) was studied as an
example of the formation of semiconductorsubstrate interface. Different possible
termination configurations were considered.
The most stable interface geometry appears
to be when N surface-terminating atom is
located above surface Si atom. Calculated
adhesion energies are presented in Table 1.
The strongest adhesion corresponds for the
case of N-termination with terminating Natom on top of surface Si atom.
Table 2. Calculated InN and GaN bandgap
in dependence from relative lattice constant
change.
-2% -1% 0%
+1% +2%
Equilibrium
value
InN 0,93 0,85 0,79
0,69 0,56
GaN 3,73 3,57 3,45
3,27 3,08
Conclusion
First-principles studies have been performed
for InN(0001)/Si(111) interface. Adhesion
energies were calculated for different
positions of atoms at interface. The
influence of strain driven lattice constant
change on InN and GaN band-gap was
studied.
References
1. X. Wang, A. Yoshikawa, Progress in
Crystal Growth and Characterization of
Materials 48/49 (2004) 42-103
2. T. A. Rawdanowicz, J. Narayan, Appl.
Phys. Let. 85 (2004) 133.
3. A.G. Bhuiyan, A. Hashimoto, A.
Yamamoto, J. Appl. Phys. 94 (2003)
2779
4. P. Hohenberg, W. Kohn, Phys. Rev. 136
(1964) B864.
5. W. Kohn, L. J. Sham, Phys. Rev. 140
(1965) A1133.
6. G.Kresse, J. Furthmuller, Phys. Rev. B
54 (1996) 11169.
7. J.P. Perdew, M. Levy, Phys. Rev. Let. 51
(1983) 1884.
8. V. I. Anisimov, F. Aryasetiawan, A. I.
Lichtenstein, J. Phys.: Condens. Matter
9 (1997) 767.
9. K. Lawniczak-Jablonska, T. Suski, I.
Gorczyca et al., Phys. Rev. B 61 (2000)
16623.
10. V.Yu. Davydov, A.A. Klyuchihin,
Fizika i tehnika poluprovodnikov 38
(2004) 897.
This work has been financed through RFBR:
grants #10-08-01263-a and #09-01-13541ofi-c.
Table 1. Adhesion energy for different
configurations
of
InN(0001)/Si(111)
interface ((0;0) – coordinate corresponds
to Si surface atom, (2/3;1/3) – next
substrate level).
Termination Coordinate of Adhesion
type
terminating
energy,
atom (In or N) J/м2
N
(1/2;0)
-0,95
N
(0;0)
-2,55
N
(1/3;2/3)
-1,01
N
(2/3;1/3)
-0,59
In
(1/2;0)
-1,69
In
(0;0)
-1,61
In
(1/3;2/3)
-1,67
In
(2/3;1/3)
-1,57
Since Si(111) and InN equilibrium lattice
constants (3,82 Å and 3.15 Å respectively)
are different, interface formation is followed
by significant stress distribution. Lattice
mismatch effects strongly the electronic
properties of nitride film, particularly the
band-gap. Thus we performed calculations
of band-gap dependence on the lattice
constant. Generally, our calculations reveal
a strong influence of the lattice constant on
band-gap value (see Table 2). In particular,
the decreasing of lattice constant up to 2%
led to the bandgap broadening up to 17% for
InN and 8% for GaN, while the increasing
of lattice constant up to 2% resulted in 29%
and 13% narrowing of bandgap for InN and
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