* Correspondence address. Dipartimento di Ingegneria dell'Innovazione, Universita` di Lecce, Via Arnesano, I-73100 Lecce, Italy. Tel.: #39-0832-320-250; fax: #39-0832-320-525. E-mail address: nico.lovergine@unile.it (N. Lovergine). Journal of Crystal Growth 221 (2000) 758}764 Detailed thermal boundary conditions in the 3D #uid-dynamic modelling of horizontal MOVPE reactors R. Mucciato, N. Lovergine* Istituto Nazionale per la Fisica della Materia (INFM), Via Arnesano, I-73100 Lecce, Italy Dipartimento di Ingegneria dell+Innovazione, Universita % di Lecce, Via Arnesano, I-73100 Lecce, Italy Abstract A three-dimensional (3D) detailed heat transfer model describing the e!ective thermal behaviour and #uid dynamics of a horizontal metalorganic vapour-phase epitaxy (MOVPE) reactor chamber is reported. Both H  conduction and convection were considered, along with the presence of a cooling H  #ow outside the main MOVPE chamber, the quartz heat conduction through the chamber walls and the convective heat transfer to the ambient air. Computational #uid-dynamic (CFD) simulations indicated that relatively large gas temperature gradients occur normal to the wafer surface both in the process and cooling gas. In the former a fully developed thermal pro"le is observed. Reduced temperature gradients occur instead in the lateral directions within the process gas #ow, giving rise to a good lateral uniformity of the temperature "eld close to the susceptor. However, large gradients build up in the cooling gas as a result of heat transfer to the surrounding ambient by the free convection. Correspondingly, large buoyancy appears in the cooling #ow. A laminar behaviour is instead obtained for the process #ow, although the substrate rotation introduces an asymmetry of the gas pathlines above the wafer. Comparing simulated susceptor-ceiling temperature di!erences (¹) with experimental ones indicates that a free convection parameter +7.5 W/m K occurs for our system. This is consistent with Ra&10 for the ambient outside the MOVPE chamber, suggesting subcritical-free convection condi- tions. CFD simulations performed as a function of susceptor temperature show close agreement between simulated and experimental ¹, indicating the usefulness of a 3D detailed heat transfer approach for the correct simulation of temperature "elds in a horizontal MOVPE reactor.  2000 Elsevier Science B.V. All rights reserved. PACS: 47.25.Qv; 81.15.Gh Keywords: MOVPE; 3D modelling; Detailed heat transfer; Computational #uid dynamics 1. Introduction Speci"c thermal boundary conditions used for the #uid-dynamic modelling of metalorganic vapour-phase epitaxy (MOVPE) horizontal reac- tors have a strong in#uence on the results of both velocity and temperature "elds obtainable by the computational simulations of these chambers. Two simpli"ed boundary conditions at the chamber side or top walls have been most often used in the literature, i.e. (i) isothermal [1,2] or (ii) adiabatic [3,4], as they allow simpli"ed modelling and reduced computational requirements. However, 0022-0248/00/$ - see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 0 2 4 8 ( 0 0 ) 0 0 8 1 2 - 5