Structural properties of AlxGa1-xN grown on sapphire by molecular beam epitaxy

Structural properties of AlxGa1-xN epilayers grown on (0 0 0 1) sapphire su bstrate by molecular beam epitaxy are investigated in the range of A1N mola r fraction from 0.16 to 0.76. The A1N molar fraction estimated by X-ray dif fraction agrees well with that of Rutherford backscattering spectroscopy, s howing a good linear relationship. The uniform Auger electron spectroscopy depth profile and linear dependence of average atomic concentration of all the constituents of AlxGa1-xN epilayers on A1N molar fraction imply that th e growth of AlxGa1-xN epilayers with variation of A1N molar fraction is wel l controlled without the compositional fluctuation in depth of the epilayer . It is observed by atomic force microscopy that the surface grain shape of AlxGa1-xN epilayer changes from roundish to a coalesced one with increasin g A1N molar fraction. (C) 2000 Elsevier Science B.V. All rights reserved.