Metal organic vapor phase epitaxy of $$\hbox {Ge}_{1}\hbox {Sb}_{2}\hbox {Te}_{4}$$Ge1Sb2Te4 thin films on Si(111) substrate

Abstract

Metal organic vapor phase epitaxy was employed for the growth of homogeneous and coalesced $$\hbox {Ge}_{1}\hbox {Sb}_{2}\hbox {Te}_{4}$$ thin films on Si(111) substrate. The influence of substrate pre-annealing on the layer morphology and composition was investigated. The annealing in $$\hbox {H}_{2}$$ atmosphere in the presence of Te is important for the deposition of smooth layers. Te atoms passivate Si surface and support van der Waals epitaxy. The growth starts with van der Waals gap followed directly by $$\hbox {Ge}_{1}\hbox {Sb}_{2}\hbox {Te}_{4}$$ layer. The morphology of epitaxial material is sensitive to the gas velocity in the reactor during growth. Measured by atomic force microscope, root mean square roughness of grown $$\hbox {Ge}_{1}\hbox {Sb}_{2}\hbox {Te}_{4}$$ layers decreases significantly when the total gas flow in the reactor increases from 2100 to 2500 sccm. The layer composition depends strongly on the growth temperature. X-ray diffraction and energy dispersive X-ray spectroscopy confirm that the composition of the material shifts toward lower Ge content with the increase of the growth temperature. The material of the interest, its composition as well as surface morphology, exhibits high sensitivity to the growth conditions.