Electrical and structural characteristics of chromium thin films deposited on glass and alumina substrates

Parallel (in-plane) electrical resistivities of single-layered Cu and Cr films, and Cu/Cr multilayered thin films sputter deposited on Si substrates were evaluated as a function of layer thicknesses ranging from 2.5 to 150 nm in the temperature range of 4–325 K. The resistivity of the multilayers at a given temperature increased and residual resistivity ratio decreased with decreasing layer thicknesses. At 300 K, the resistivity of a 1 μm thick Cu film was approximately equal to the bulk value, but the resistivity of the Cr film was an order of magnitude higher than that of bulk Cr. The microstructures of the multilayers and the single-layered Cu and Cr thin films were characterized by transmission electron microscopy. For layer thicknesses ranging from 2.5 to 150 nm, the multilayers exhibited sharp, planar interfaces between the two phases. The individual Cu and Cr layers were nanocrystalline with near-equiaxed grains in Cu and columnar grains in Cr. The dependence of electrical resistivity on the layer ...

Electrical resistivity of sputtered Cu/Cr multilayered thin films

Chromium thin films obtained by evaporation in a vacuum bell-jarr have different reactive properties. In order to determine these ones six techniques are used: X-rays and electron diffractions to study the crystallographical structures; EELS, AES, ESCA, and GXR (grazing X-ray reflection) methods in order to approach the chemical composition. The results permit to show the formation of compounds such as a suboxide (Cr3O) with a primitive cubic cell (A-15 type) and a hydrated oxyhydroxide with a rhombohedral structure. This study leads to show that the „new modification of chromium”, as „NMCr”, cannot be the metal itself.



Les couches minces de chrome obtenues par evaporation sous vide presentent des proprietes reactives diverses. Afin de les determiner nous avons utilise six techniques differentes: la diffraction de rayons-X et la diffraction electronique pour etudier les structures cristallographiques; et les methodes de mesures: EELS, AES, ESCA et GXR (rayons-X rasants par reflection) pour approcher la composition chimique. Les resultats ont permis de mettre en evidence la formation de plusieurs composes: un sous-oxyde de composition „Cr3O” de structure cubique primitive (type A-15) et un oxyhydroxyde hydrate de structure rhomboedrique. Cette etude a conduit a montrer que la „nouvelle modification du chrome”, appelee „NMCr”, ne peut etre assimilee au metal luiměme.

Analysis and crystallographic structures of chromium thin films

We have prepared thin (50–1500 A) polycrystalline films of Cr by vacuum (10−8 Torr) evaporation methods using the deposition rate on Corning glass 7059 and its temperature as experimental parameters. Electrical resistivity (ρ) of these films has been studied in situ as a function of temperature (T), film thickness (t), and the above preparation variables. Our films exhibit well‐definied anomalies at the Neel temperature which is strongly dominated by internal stresses. The ρ vs T curves are briefly compared with those of other investigators.

Electrical conduction in thin chromium films

Itinerant electron surface magnetism

Thin films of Cr were deposited on glass substrates at 20°C, 50°C, 100°C and 250°C in a vacuum of about 5×10 -5 Torr. Their structural and electrical properties were investigated by means of the transmission-electron microscopy, electron diffraction and resistivity measurement. Films deposited at 100°C show the same anomaly in the electrical resistivity as that observed in the plastically deformed Cr. The Neel temperature T N , obtained from the resistivity anomaly, increases with decreasing film thickness. This shift in T N , being related to the tension due to the residual strain developed in the films, is explained in terms of the variation of the critical yield stress. In relation to the uncommensurate-commensurate transition of the spin density wave, a discussion is made on the extremely large anomaly in the resistivity of films deposited at 20°C, which consist of very fine sub-grains with an average diameter smaller than the period of the spin density wave.

Hitoshi Hara

Papers

Size Effects on the Spin Density Wave in Cr Films