Soft-Impact, Ltd. (SI) was founded in 1996 to undertake development of software, engineering consulting and other activities related to crystal growth and thin film deposition. The core staff working for the company had been formed in 1994-1996 while carrying out several international research projects funded by the Commission of European Community, Ministry of Science and Technology of Germany and Volkswagen Foundation.

The SI’s team is involved into theoretical studies of group III-Nitride growth since 1996. Its activity covers various growth techniques - MBE, MOCVD, sublimation growth of GaN and AlN and Chloride HVPE. This allows them to understand in details the basic growth mechanisms specific for the group III-Nitrides. In particular, this is the only team who has attempted to account for kinetics of the adsorption and desorption processes in growth, what is especially important for these materials.

The general strategy of the Soft-Impact team is the building of theoretical models with the minimum number of parameters required to fit the experimental data. This has been achieved by verifying the same model for very different conditions. For example, the main ideas developed for the MBE process were successfully used for the analysis of MOCVD or sublimation growth of the group III-Nitrides. Such generality ensures that the models being developed adequately describe the real experimental situation.

The primary equipment available at Soft-Impact facility includes a number of high power Pentium II and Pentium III computers and specialized software, that can provide 2D/3D calculations for successful fulfillment of the project.

Relevant publications

1. Averyanova M.V., Karpov S.Yu., Przhevalsky I.N., Makarov Yu.N., Ramm M.S. Talalaev R.A.Analysis of vaporization kinetics of group-V nitrides. Material Sci. Engineer. B, 1997, 43, p.167-171
2. Karpov S.Yu., Maiorov M.A. Model of the adsorption/desorption kinetics on growing III-V compound surface. Surf.Sci., 1997, 393(1), 108-125
3. Karpov S. Yu., Makarov Yu.N., Ramm M.S., Talalaev R.A. Analysis of gallium nitride growth by gas-source molecular beam epitaxy. J.Cryst.Growth, 1998, 187(3/4), 397-401
4. Karpov S.Yu., Makarov Yu.N., Ramm M.S. Effect of elastic strain on growth of ternary group-III nitride compounds. Mat.Sci.Forum, 1998, 264/268, 1189-1192
5. Karpov S.Yu., I.N.Przhevalsky, Yu.N.Makarov. Thermodynamic properties of group-III nitrides and related species. MRS J. Nitride Semicond. Res. 1998, 3, No 30.
6. P.G.Baranov, Karpov S.Yu., E.N.Mokhov, A.O.Ostroumov, M.G.Ramm, M.S.Ramm, V.V.Ratnikov, A.D.Roenkov, Yu.A.Vodakov, A.A.Wolfson, G.V.Saparin, D.V.Zimina, Yu.N.Makarov, H.Jü rgensen. Current status of GaN crystal growth by sublimation sandwich technique. MRS J. Nitride Semicond. Res. 1998, 3, No 50.
7. N.Grandjean, Karpov S.Yu., J.Massies, F.Semond, R.A.Talalaev. GaN evaporation in molecular beam epitaxy environment. Appl.Phys.Lett. 1999, 74(13), 1854-1856.
8. Karpov S.Yu., R.A.Talalaev, E.V.Yakovlev, Yu.N.Makarov, O.Schö n, M.Heuken, G.Strauch, H.Jü rgensen. Modeling of InGaN MOVPE in AIX 200 Reactor and AIX 2000 HT Planetary Reactor. MRS J. Nitride Semicond. Res. 1999, 4, No 5.
9. Karpov S.Yu., V.G.Prokofjev, E.V.Yakovlev, R.A.Talalaev, Yu.N.Makarov. Novel approach to simulation of group-III nitrides growth by MOVPE. MRS J. Nitride Semicond. Res. 1999, 4, No 4.

Current status of the project. Up to date, we have developed and verified an advanced model of III-nitride HVPE, based on the quasi-thermodynamic approach. The model is applied to analysis of various reactor designs reported in the literature. As a result, two perspective vertical reactors have been selected for further careful modeling and optimization. For one of them, that is an axially symmetric reactor with co-axial species supply, a preliminary 2D optimization is carried out, the optimal species fluxes and reactor sizes are found approximately. For the other reactor, that is an asymmetric reactor with supply of the reactive species through two parallel tubes, a detailed 3D modeling is performed, features of the process in reactors of this type are revealed and studied.