N. Lemee et al., Influence of the deposition parameters on the characteristics of CuxMo6S8 thin films in situ grown by pulsed laser deposition, MAT SCI E B, 72(1), 2000, pp. 47-55
CuxMo6S8 thin films have been grown in situ by pulsed laser deposition (PLD
) on R-cut Al2O3 single-crystal substrates. Under selected deposition condi
tions, they are oriented and present epitaxial relationships with the in-pl
ane substrate directions. The influence of deposition parameters on composi
tion or epitaxial quality has been studied in detail. In most samples, an e
xcess of metallic molybdenum has been detected by X-ray diffraction and qua
ntified by Rutherford backscattering spectrometry (RBS). The deposition und
er argon (8.10(-2) mbar) at 870 degrees C with a target-substrate distance
of 38 mm and an average laser fluence of 5 J cm(-2), has entailed a signifi
cant reduction of this secondary phase. Moreover, using a small-sized, home
made vacuum chamber, single-phased CuxMo6S8 films have been in situ grown
for the first time. The epitaxial relations have been investigated by X-ray
diffraction in various modes (namely theta-2 theta, theta-scans and phi-sc
ans) and by scanning electron microscopy. Under secondary vacuum, (100)(Rh)
oriented thin films are obtained above 820 degrees C and a progressive imp
rovement of the epitaxial growth has been observed up to 890 degrees C. The
superconducting critical temperature T-c, measured by the a.c. susceptibil
ity method, appears insensitive to the microstructural modifications. Such
deposition conditions have been applied to other substrates like Al2O3-C, (
100) MgO or (100) Y: ZrO2 and have led to new complex epitaxial growth rela
tions. (C) 2000 Elsevier Science S.A. All rights reserved.