Growth of very uniform silicon carbide epitaxial layers

In a method of forming epitaxial layers of silicon carbide on a plurality of appropriate substrates by chemical vapor deposition by:

• blending silicon carbide source gases are with a first carrier gas;
• directing the source gases into a reactor that contains a plurality of substrates linearly arranged along the gas flow path in the reactor so that the carrier and source gases flow over the substrates in an upstream to downstream orientation parallel to the epitaxial growth surface;
• and
• heating the reactor to a temperature at which the source gases will react to form an epitaxial layer of silicon carbide on the substrates in the reactor;
• the improvement that comprises:
• blending a second carrier gas with the first carrier gas, and in which the second carrier gas has a thermal conductivity that is less than the thermal conductivity of the first carrier gas, and wherein the second carrier gas is present in an amount that moderates the temperature sufficiently to reduce or eliminate source gas depletion during the growth of epitaxial layers of silicon carbide on the substrates, but less than an amount that would reduce the temperature sufficiently to prevent the source gases from reacting to form the epitaxial layer.