Electrical properties of AlNxOy thin films prepared by reactive magnetron sputtering

• Published in: Thin solid films Vol. 520; no. 21; pp. 6709 - 6717
• Main Authors: Borges, J., Martin, N., Barradas, N.P., Alves, E., Eyidi, D., Beaufort, M.F., Riviere, J.P., Vaz, F., Marques, L.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.08.2012; Elsevier
• Subjects: Acoustics; Aluminum oxynitride; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Electrical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Engineering Sciences; Exact sciences and technology; Magnetron sputtering; Materials; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Micro and nanotechnologies; Microelectronics; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Electrical properties; Aluminum oxynitride; Magnetron sputtering; Grain size; Oxynitrides; Cubic lattices; Semiconductor materials; Ternary systems; Polycrystals; Aluminium; Deposition rate; XRD; Gas mixtures; Thin films; Cathode sputtering; Transmission electron microscopy; Partial pressure; Morphology; Physical vapor deposition; Reactive sputtering; Sputter deposition; Gallium selenides
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2012.06.062

Direct current magnetron sputtering was used to produce AlNxOy thin films, using an aluminum target, argon and a mixture of N2+O2 (17:3) as reactive gases. The partial pressure of the reactive gas mixture was increased, maintaining the discharge current constant. Within the two identified regimes of the target (metallic and compound), four different tendencies for the deposition rate were found and a morphological evolution from columnar towards cauliflower-type, ending up as dense and featureless-type films. The structure was found to be Al-type (face centered cubic) and the structural characterization carried out by X-ray diffraction and transmission electron microscopy suggested the formation of an aluminum-based polycrystalline phase dispersed in an amorphous aluminum oxide/nitride (or oxynitride) matrix. This type of structure, composition, morphology and grain size, were found to be strongly correlated with the electrical response of the films, which showed a gradual transition between metallic-like responses towards semiconducting and even insulating-type behaviors. A group of films with high aluminum content revealed a sharp decrease of the temperature coefficient of resistance (TCR) as the concentration ratio of non-metallic/aluminum atomic ratio increased. Another group of samples, where the non-metallic content became more important, revealed a smooth transition between positive and negative values of TCR. In order to test whether the oxynitride films have a unique behavior or simply a transition between the typical responses of aluminum and of those of the correspondent nitride and oxide, the electrical properties of the ternary oxynitride system were compared with AlNx and AlOy systems, prepared in similar conditions. ► AlNxOy thin films were produced using magnetron sputtering. ► AlNxOy film morphology, composition and structure depend on reactive gas pressure. ► Electrical properties can be tuned controlling the non metallic/metallic ratio.