HVPE growth in horizontal flow reactor has been analyzed using finite element calculation and molecular estimates of the reaction rates. The reaction rate of the HCl with liquid Ga has been estimated using ideal gas approximation for HCl vapor. The conversion HCl to GaCl rate has been obtained in function of the pressure, temperature, flow velocity and the geometry of the reactor.

Finite element code FIDAP (commercially available from Fluent Inc.) has been used to calculate the flow pattern in the reactor. In the first approximation it was assumed that the flow pattern is weekly dependent on the temperature distribution in the reactor. It was also assumed that the volume reaction rates can be approximated by temperature independent reaction constants.

Using these calculation it was possible to obtain the reaction rates on the susceptor surface. The reaction rate leads to different growth rates depending on the geometry of the susceptor and the distance between the flow outlets. The calculated reaction rates were compared with the measured growth rate in horizontal, normal pressure HVPE reactor.

Additionally , the parasitic reaction on the pipe close to the gas inlets was observed. It was shown that the reaction is strongly inhomogeneous, depending on the geometry of the inlets. The reaction depends on the flow velocity and the pressure. The obtained reaction rates were compared with the estimates drown from the growth experiments.