In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge 2 Sb 2 Te 5 (GST) and In 3 Sb 1 Te 2 (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point R s measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point R s data. In addition, in In 28 Ge 12 Sb 26 Te 34 , multiple V th values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In 2 Te 3 occurred in all of the InGeSbTe samples after annealing at 350°C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge-Te, In-Te, Sb-Te, In-Sb and In-In bond energies.
Bibliographical noteFunding Information:
This research was supported by a grant from the Fundamental R&D Program for Core Technology of Materials and the National Research Project for “Development of High Performance Phase Change Materials” of the Ministry of Knowledge Economy, Republic of Korea .
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films