Method of growing a buffer layer using molecular beam epitaxy

A method of growing a Group III-V nitride buffer layer on a substrate made of a different material by molecular beam epitaxy to compensate for lattice mismatching between a material of the substrate and a material of a further layer to be grown on the substrate, the method comprising of the steps of:

• placing the substrate in a vacuum chamber in the pressure range of from 10−2 to 10 −9 Pa and at an elevated temperature;
• and
• supplying species to the vacuum chamber to be used in the epitaxial growth including a nitrogen precursor species supplying nitrogen to the substrate to cause epitaxial growth on the substrate of the buffer layer,
• wherein said elevated temperature is in the range of 300 to 800° C., and the flow rate of the nitrogen precursor is selected to be approximately from 2 to 15 sccm whereby a supply rate of nitrogen to the substrate is such as to cause epitaxial growth on the substrate Group III-V nitride buffer layer of uniform thickness less than 2000 Å at a growth rate in the range of 2 to 10 μm/hr.