Niobium and zirconium telluride thin films prepared by sputtering
- PDF / 254,001 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 8 Downloads / 325 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Niobium and zirconium telluride thin films prepared by sputtering Daniel Pailharey and Yves Mathey CNRS UMR 6631, Facult´e des Sciences de Luminy, Universit´e de la M´editerran´ee, F-13288 Marseille, Cedex 9, France
Mohamad Kassem CNRS UMR 6631, Facult´e des Sciences de Luminy, Universit´e de la M´editerran´ee, F-13288 Marseille, Cedex 9, France and Department of Chemistry, Atomic Energy Commission of Syria, B.P. 6091, Damas, Syria (Received 8 December 1997; accepted 12 November 1998)
A versatile procedure of sputter deposition, well-adapted for getting a large range of TeyM ratios (with M Zr or Nb), has led to the synthesis of several highly anisotropic zirconium and niobium polytellurides in thin film form. Upon tuning the two key parameters of the process, i.e., the Te percentage in the target and the substrate temperature during the deposition, preparation of systems ranging from ZrTe0.72 to ZrTe6.7 , on the one hand, and from NbTe1.28 to NbTe7.84 , on the other, has been achieved. Besides their amorphous or crystalline (with or without preferential orientations) behavior and their relationship to known structural types, the most striking feature of these films is their large departure from the stoichiometry of the bulk MTex reference compounds. This peculiarity, together with the possible changes of composition under annealing, are described and interpreted in terms of variable amounts of Te and M atoms trapped or intercalated within the parent structures.
I. INTRODUCTION
The low-dimensional character of the early transition metal chalcogenide structures has been largely documented, and many examples of their strong optical, electrical, and chemical anisotropies are known.1 The growth of such systems in thin film form has also been performed by means of several techniques. As a matter of fact, film deposition of sulfides MSx and selenides MSex of group IV to VI transition metals has been successfully carried out by molecular beam epitaxy techniques2 as well as by sputtering3 and plasma chemical vapor deposition (CVD) methods.4 Nevertheless, as far as lowdimensional telluride systems are concerned, and despite their rather new or peculiar behavior with respect to the corresponding sulfides or selenides,5 very few film growth experiments have been reported yet. A preliminary study, related to the remarkable lubricative behavior of some NbTe2 -like deposits,6 has shown how important it is to get better insight into the deposition conditions of this new class of inorganic coatings when it is desired to take advantage of their anisotropy. We have undertaken, therefore, the synthesis of zirconium and niobium telluride MTex films7 on several types of substrates by using a sputtering technique. Crystalline or amorphous deposits with different stoichiometries and thermal behavior were obtained in the (0.8–5) TeyM atomic ratio range. Although discrete values (4y5, 4y3, 2, 3, 4, and 5), corresponding to known crystalline and stable binary phases, could be expected,1,8–11
Data Loading...
