Growth of epitaxial semiconductor material with improved crystallographic properties

A method of forming an epitaxial semiconductor layer on a semiconductor substrate, the method comprising.

• placing a silicon substrate having a front surface within an epitaxial reaction chamber;
• adjusting the temperature of the substrate to a first temperature suitable for epitaxial silicon growth;
• flowing a first flow of source gas into the reaction chamber at a first flow rate to grow a first epitaxial silicon layer on the front surface of the substrate to cover crystallographic defects in the front surface;
• adjusting the temperature of the substrate to a second temperature suitable for epitaxial silicon growth, where the second temperature is lower than the first temperature;
• and
• flowing a second flow of source gas into the reaction chamber at a second flow rate when the substrate is at the second temperature to grow a second epitaxial silicon layer on the first layer, where the second flow rate is higher than the first flow rate;
• where the first and second layers each have a thickness, and the second layer is thicker than the first layer.