Structure and electronic properties of AlCrOxN1 − x thin films deposited by reactive magnetron sputtering

• AlCr(OxN1 − x) layers with variable oxygen content 0 < x < 1 were grown.
• The layers with the lowest oxygen content, x < 0.6, electronically behave like nitrides.
• Coatings with 0.6 ≤ x < 0.97 are assigned to metastable monoxides.
• The oxide region consisted of a solid solution of α-phase with a corundum structure.

In this study, the main attempt is devoted to investigating the microstructure and electronic properties of AlCrOxN1 − x films in a wide range of oxygen concentrations from 0 to 1. These oxynitride films were deposited by pulsed DC magnetron sputtering from Al55Cr45 targets. Our results showed that films with x = O/(O + N) < 0.6, exhibit a cubic (B1) lattice with a well-developed columnar structure. The incorporation of oxygen into the films without any oxide segregation results in the formation of a substitutional AlCrOxN1 − x solid solution and material system behaves like nitrides electronically. In the range of oxygen contents from 0.6 ≤ O/(O + N) < 0.97, coatings with fine columns, diffuse boundaries and high values of metal vacancies were formed. However, the B1 lattice survived despite the large proportion of oxygen. According to the structural and electronic properties of the corresponding layers, we assign this region to the formation of an amorphous phase and metastable monoxides with a B1 structure. Coatings with O/(O + N) ≥ 0.97 are electronically assigned to a solid solution of α-(Al,Cr)2(O0.97,N0.03)3 with corundum lattice and finer columnar structure.