Chemical Bonding Characteristics of Ge ₂Sb ₂Te ₅ for Thin Films

The chalcogenide-based phase change memory has been suggested as an alternative non-volatile memory device at the 180 nm technology node. These materials appear to have a reversable phase change between amorphous and crystalline phasees. A sputtered Ge ₂Sb ₂Te ₅ film is deposited on a (100) Si substrate. In order to investigate the crystallization tendency at a certain temperature, we use X-ray diffraction and X-ray photoelectron spectroscopy. The film morphology is observed by using atomic forces microscopy. Grain growth and a phase transition from cubic to hexagonal occurs when the films are heated from 170°C and 380°C, and Ge-Te and Te-Sb bonds increased with annealing.