Real-time control of AlN incorporation in epitaxial Hf1-xAlxN using high-flux, low-energy (10-40 eV) ion bombardment during reactive magnetron sputter deposition from a Hf0.7Al0.3 alloy target

• The AlN incorporation probability in single crystal Hf-1 (-) xAlxN(0 0 1) layers is controllably adjusted between similar to 0% and 100% by varying the ion energy (E-i) incident at the growing film over a narrow range, 10-40 eV. The layers are grown on MgO(0 0 1) at 450 degrees C using ultrahigh vacuum magnetically unbalanced reactive magnetron sputtering from a Hf0.7Al0.3 alloy target in a 5%-N-2/Ar atmosphere at a total pressure of 20 mTorr (2.67 Pa). 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 = 10 eV, to 0.27 with E-i = 20 eV, 0.17 with E-i = 30 eV, and andlt;= 0.002 with E-i andgt;= 40 eV. 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.

Keyword

Sputter deposition

Ion bombardment

Transition metal nitrides

HfAlN

Nanolayers

TECHNOLOGY

TEKNIKVETENSKAP

Publication and Content Type

ref (subject category)

art (subject category)