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A narrow growth window combined with highly temperature dependent compositional variations poses a serious problem for the growth of epitaxial GeTe–Sb2Te3 (GST) thin films. The problems are further aggravated by the weak coupling of the radiatively heated non-contact thermocouples to the substrate. An increase in surface temperature during growth as inferred from the increase in desorption of GeTe heteromolecules and the resulting change in alloy composition are studied. Using the desorption signal as a feedback to control the surface temperature, the thermocouple temperature was varied over the duration of the growth to maintain a constant desorption and hence constant surface temperature. Interestingly, the composition of the grown films varies along the GeTe–Sb2Te3 pseudobinary line just by varying the desorption without changing the supplied flux. The out-of-plane lattice constant of the …
Publication date: 
15 Jun 2014

Karthick Perumal, Wolfgang Braun, Henning Riechert, Raffaella Calarco

Biblio References: 
Volume: 396 Pages: 50-53
Journal of crystal growth