Boron-Containing Buffer Layer for Growing Gallium Nitride on Silicon

摘要

A silicon wafer used in manufacturing GaN for LEDs includes a silicon substrate, a buffer layer of boron aluminum nitride (BxAl1-xN) and an upper layer of GaN, for which 0.35≦̸x≦̸0.45. The BAlN forms a wurtzite-type crystal with a cell unit length about two-thirds of a silicon cell unit length on a Si(111) surface. The C-plane of the BAlN crystal has approximately one atom of boron for each two atoms of aluminum. Across the entire wafer substantially only nitrogen atoms of BAlN form bonds to the Si(111) surface, and substantially no aluminum or boron atoms of the BAlN are present in a bottom-most plane of atoms of the BAlN. A method of making the BAlN buffer layer includes preflowing a first amount of ammonia equaling less than 0.01% by volume of hydrogen flowing through a chamber before flowing trimethylaluminum and triethylboron and then a subsequent amount of ammonia through the chamber.