In-Sb-Te 박막의 결정화 거동에 관한 투과전자현미경 연구

Abstract

The phase change materials have been extensively used as an optical rewritable data storage media utilizing their phase change properties. Recently, the phase change materials have been spotlighted for the application of non-volatile memory device, such as the phase change random access memory. In this work, we have investigated the crystallization behavior and microstructure analysis of In-Sb-Te (IST) thin films deposited by RF magnetron sputtering. Transmission electron microscopy measurement was carried out after the annealing at 300􀆆C, 350􀆆C, 400􀆆C and 450􀆆C for 5 min. It was observed that InSb phases change into In3SbTe2 phases and InTe phases as the temperature increases. It was found that the thickness of thin films was decreased and the grain size was increased by the bright field transmission electron microscopy (BF TEM) images and the selected area electron diffraction (SAED) patterns. In a high resolution transmission electron microscopy (HRTEM) study, it shows that 350􀆆C-annealed InSb phases have {111} facet because the surface energy of a {111} close-packed plane is the lowest in FCC crystals. When the film was heated up to 400􀆆C, In3SbTe2 grains have coherent micro-twins with {111} mirror plane, and they are healed annealing at 450􀆆C. From the HRTEM, InTe phase separation was occurred in this stage. It can be found that In3SbTe2 forms in the crystallization process as composition of the film near stoichiometric composition, while InTe phase separation may take place as the composition deviates from In3SbTe2.