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.

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.

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.

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.

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.

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).

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).

Advances in the modeling of MOVPE processes.
S. Yu. Karpov.
J. Crystal Growth, Vol.248, p.1-7, (2003).

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).

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).

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).

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).

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).

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).

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).