Search

Abstract: The AlN incorporation probability in single crystal Hf1− x Al x N(001) layers is controllably adjusted between ∼0% and 100% by varying the ion energy (E i) incident at the growing film over a narrow range, 10–40eV. The layers are grown on MgO(001) at 450°C using ultrahigh vacuum magnetically unbalanced reactive magnetron sputtering from a Hf0.7Al0.3 alloy target in a 5%-N2/Ar atmosphere at a total pressure of 20mTorr (2.67Pa). The ion to metal flux ratio incident at the growing film is constant at 8. Epitaxial film compositions vary from x =0.30 with E i =10eV, to 0.27 with E i =20eV, 0.17 with E i =30eV, and ⩽0.002 with E i ⩾40eV. Thus, the AlN incorporation probability decreases by greater than two orders of magnitude. This extraordinary range in real-time manipulation of film chemistry during deposition is due to the efficient resputtering of deposited Al atoms (27 amu) by Ar+ ions (40 amu) neutralized and backscattered from heavy Hf atoms (178.5 amu) in the film. This provides a new reaction pathway to synthesize, at high deposition rates, compositionally complex heterostructures, multilayers, and superlattices with abrupt interfaces from a single alloy target by controllably switching E i. For multilayer and superlattice structures, the choice of E i value determines the layer composition and the switching periods control the individual layer thickness. [ABSTRACT FROM AUTHOR]