Growth of crack-free hexagonal GaN films on Si(100)

Hexagonal GaN films have been grown on Si(100) substrates by employing a sp uttered AlN buffer layer followed by another high-temperature metalorganic chemical vapor deposition (MOCVD) grown AlN buffer layer. The highly orient ed structure of sputtered AlN provides a hexagonal template for subsequent AlN and GaN growth. The GaN films are evaluated by transmission electron mi croscopy, selected area electron diffraction, x-ray diffraction, and photol uminescence and exhibit a purely hexagonal columnar structure. The orientat ion of the GaN columns depends on the thickness of both the sputtered AlN b uffer layer and the MOCVD grown AlN buffer layer. The surface of GaN films is shiny and crack free up to a thickness of 2 mum studied in this work. (C ) 2001 American Institute of Physics.