On the 2D modelling of horizontal CVD reactors and its limitations
Abstract
In order to clarify under what conditions 2D theoretical models can realistically account for the actual growth rate distribution in horizontal CVD reactors, we have performed a systematic numerical study and compared the results with published experimental data for the MOCVD of gallium arsenide. Three models of increasing complexity were studied. It is shown that 2D models can produce realistic predictions only for reactors with large width-to-height (aspect) ratios, that are operated at subcritical Rayleigh number, i.e. under dominant forced flow conditions. But even then, depending on the carrier gas, thermal (Soret) diffusion must be included in the model. Furthermore, velocity corrections for finite aspect ratios must be made, and buoyancy effects can be significant in the entrance region. On the other hand, the results are relatively insensitive to axial diffusion, temperature dependence of transport properties (versus averaged properties), and an assumed Poiseuille velocity profile (versus a rigorous solution of the velocity field). Yet, boundary layer approximations are prone to give unrealistic results at the low Reynolds numbers typical for CVD operations.
- Publication:
-
Journal of Crystal Growth
- Pub Date:
- September 1988
- DOI:
- 10.1016/0022-0248(88)90117-0
- Bibcode:
- 1988JCrGr..91..497O
- Keywords:
-
- Gallium Arsenides;
- Gas-Solid Interfaces;
- Soret Coefficient;
- Two Dimensional Models;
- Vapor Deposition;
- Aspect Ratio;
- Microgravity Applications;
- Rayleigh Number;
- Reynolds Number;
- Space Commercialization;
- Temperature Dependence;
- Solid-State Physics