Patent ID: 7598108

Claim:
A method for forming a thermal expansion interface between silicon (Si) and gallium nitride (GaN) films using multiple buffer layers of aluminum compounds, the method comprising: providing a ( 111 ) Si substrate; depositing a first layer of AIN overlying the substrate, heating the substrate to a temperature within a first range; depositing a second layer of AlN directly overlying and in contact with the first layer of AlN, hearing the substrate to a temperature within a second range, lower than the first range; depositing a third layer of AlN directly overlying and in contact with the second layer of AlN, heating the substrate to a temperature within the first range; forming a first grading Al 1-X Ga X N layer directly overlying and in contact with the third layer of AlN, where 0<X<1; forming a first fixed composition Al 1-X Ga X N layer directly overlying and in contact with the first grading Al 1-X Ga X N layer, where 0<X<1; and, growing a first epitaxial GaN layer directly overlying and in contact with the fixed composition Al 1-X Ga X N layer.