High quality GaN epilayers grown on Si (1 1 1) with thin nonlinearly composition-graded AlxGa1-xN interlayers via metal-organic chemical vapor deposition

The growth of GaN epilayers on AlN/Si (1 1 1) templates with thin nonlinearly composition-graded AlxGa1-xN interlayers via metal-organic chemical vapor deposition (MOCVD) is reported in this work. The composition-graded AlxGa1-xN interlayer was achieved by simply changing the growth condition of AlN to that of GaN layers during a fixed time. The surface morphology, crystalline quality and stress of GaN films have been investigated with different AlxGa1-xN interlayer thickness, 280 nm, 460 nm, 575 nm, and 750 nm. It was found that the properties of GaN films are highly dependent on the AlxGa1-xN interlayer thickness. High quality crack-free GaN films up to 1.2 mu m can be achieved with 460 nm thick AlxGa1-xN layer. (C) 2010 Elsevier B.V. All rights reserved.