Gas-phase processes
Elevated temperatures typically used to grow III-nitrides result in “switching on” some
physical-chemical mechanisms that are not so important for conventional III-V compounds
(see III/V MOCVD). Such phenomena as the production of adducts via reactions between
metalorganic precursors (TMGa, TMAl, TMIn, and the products of their decomposition) and
ammonia, gas-phase clustering, and formation of particles in the reactor hot zones are generally
recognized to be the source of the material losses and, therefore, to limit the growth rate
and govern largely the layer composition. In addition, these phenomena interact to each other;
their intensities may depend considerably on the operating conditions (temperature, pressure,
precursor flow rates, and residence time), so that different mechanisms may play a key role in
different reactor configurations. From an analysis of experimental observations found in the
literature, we have suggested and tested numerically various ways of material losses in group-III
nitride MOVPE. A detailed mechanism of gas-phase reactions of the initial precursor decomposition
and formation of complex molecules that do not contribute to the growth is combined to a model
of particle formation growth.
Surface processes
High temperatures used to grow III-nitrides compounds also activate a chemical mechanism
that is not pronounced during the growth of arsenides and phosphides: desorption of volatile
group-III species from the growth surface. Another important effect to be accounted for is
the elastic strain arising in the growing layer due to the lattice mismatch with underlying
GaN buffer layer.
Developed model
We have developed III-nitride MOVPE model accounting for all these gas-phase and surface
phenomena. This model demonstrates a good agreement with experimental data obtained during
the growth of epilayers in Al-Ga-In-N system used for growing heterostructures for high-electron
mobility transistors (HEMTs), light emitting diodes (LED) and laser diodes (LD). These
structures include GaN, InGaN and AlGaN epitaxial layers.
Segregation effects
Another topic in modeling is aimed at understanding growth of quantum-well device
heterostructures. Due to extremely small epilayer thickness, the transient effects originated
from the precursor switching, wafer rotation, surface kinetics, and dopant distribution
across the structure may be important. In particular, surface segregation of a volatile species,
for instance, of indium in InGaN, frequently results in a delayed In incorporation into the
crystal and in indium “tails” in the cap layer grown without the TMIn supply. We have suggested
a special unsteady model of surface segregation predicting the main factors controlling segregation
to be temperature and strain due to lattice mismatch between the epilayer and underlying wafer.
References on Models and Mechanisms of Group III-Nitride Layers
2003
Critical issues in group-III nitride MOVPE modeling.
E.V.Yakovlev, R.A.Talalaev, A.N.Vorob’ev, Yu.N.Makarov.
Electrochemical Society Proceedings, Vol. 2003-08 (2003) 258.
2001
On low temperature kinetic effects in Metal - Organic Vapor Phase Epitaxy of III-V compounds.
R.A.Talalaev, E.V.Yakovlev, S.Yu.Karpov, Yu.N.Makarov.
Journal of Crystal Growth, Vol.230, p.232-238, (2001).
Gallium droplet formation during MOVPE and thermal annealing of GaN.
O.V.Bord, S.Yu.Karpov, R.A.Talalaev, Yu.N.Makarov.
Materials Science and Engineering, Vol.B82, p.22-24, (2001).
1999
On the possible origins of low indium incorporation during MOVPE of InGaN.
R.A.Talalaev, E.V.Yakovlev, S.Yu.Karpov, I.Yu.Evstratov, A.N.Vorob’ev, and Yu.N.Makarov.
Physica Status Solidi (a), Vol.176, p.253-256, (1999).
Novel approach to simulation of group-III nitrides growth by MOVPE.
S.Yu.Karpov, V.G.Prokofyev, E.V.Yakovlev, R.A.Talalaev, Yu.N.Makarov.
MRS Internet Journal of Nitride Semiconductor Research, Vol.4, Art.4, (1999).
References on GaN and InGaN growth in the Horizontal and Planetary Reactors
2003
Advances in the modeling of MOVPE processes.
S. Yu. Karpov.
J. Crystal Growth, Vol.248, p.1-7, (2003).
1999
Modeling of InGaN MOVPE in AIX 200 Reactor and AIX 2000 HT Planetary Reactor.
R.A.Talalaev, E.V.Yakovlev, S.Yu.Karpov, Yu.N.Makarov, O.Schoen, M. Heuken, G.Strauch, Holger Juergensen.
MRS Internet Journal of Nitride Semiconductor Research, Vol.4, Art.5, (1999).
1997
Modeling of MOVPE of Group III-Nitrides in horizontal tube reactor.
A.O.Galjukov, Y.E.Egorov, Y.N.Makarov, R.A.Talalaev, C.Kirchner, M.Kamp, K.J.Ebeling.
Electrochemical Society Proceedings, Vol.97-34, p.244-253, (1997).
1996
MOCVD equipment for recent developments towards the blue and
green solid state laser.
H.Juergensen, D.Schmitz, G.Strauch, E.Woelk, M.Dauelsberg, L.Kadinski, Yu.N.Makarov.
MRS Internet Journal Nitride Semiconductor Research, Vol.1, Art.26, (1996)
GaN-MOVPE: correlation between computer modelling and experimental data.
M.Dauelsberg, L.Kandinski, Yu.N.Makarov, E.Woelk, G.Strauch, D.Schmitz, H.Juergensen.
Institute of Physics Conference Series Vol.142, 887 (1996).
References on Thermodynamic Properties
1998
Suppression of phase separation in InGaN due to elastic strain.
S.Yu.Karpov.
MRS Internet Journal of Nitride Semiconductor Research, Vol.3, Art.16, (1998).
Thermodynamic properties of group-III nitrides and related species.
S.Yu.Karpov, I.N.Przhevalsky, Yu.N.Makarov.
MRS Internet Journal of Nitride Semiconductor Research, Vol. 3, Art.30, (1998).
References on Segregation in InGaN/GaN heterostructures
2003
Segregation effects and bandgap engineering in InGaN quantum-well heterostructures.
K.A. Bulashevich, R.A. Talalaev , S.Yu. Karpov, I.Yu. Evstratov, and Y.N. Makarov.
Materials Research Society Symposium Proceedings, Vol.743, p.L6.5.1-L6.5.6, (2003).
2002
Indium segregation in MOVPE grown InGaN based heterostructures.
R.A. Talalaev, S.Yu. Karpov, I.Yu. Evstratov, Yu.N. Makarov.
Physica Status Solidi (c), Vol.01, p.311-314 , (2002).
Indium segregation kinetics in MOVPE of InGaN-based heterostructures.
S.Yu. Karpov, R.A. Talalaev, I.Yu. Evstratov, and Yu.N. Makarov.
Physica Status Solidi (a), Vol.192, N 2, p.417-423, (2002).
2001
Surface Segregation and Composition Fluctuations in ammonia MBE and MOVPE of InGaN.
S.Yu.Karpov, R.A.Talalaev, E.V.Yakovlev and Yu.N.Makarov.
Mat.Res.Soc.Proc., Vol.639, p.G3.18.2-G3.18.6, (2001).
