The effect of Ge addition on the RESET operation of a phase-change memory (PCM) device using Ge-doped SbTe

Using Ge-doped SbTe (Ge–ST) materials of a fixed Sb:Te ratio (∼4.4), we investigated the effects of Ge addition (0–13.1 at.%) with a particular regard to the possibility of achieving highly fast and reliable programming characteristics of a phase-change memory device. From material characterization, we found that a higher Ge content led to the enhanced stability of the amorphous phase state and retarded nucleation of crystallites but the growth of crystallites remained very fast regardless of Ge content. Consistent with these findings, examination of device characteristics revealed that, with increasing Ge content up to 13.1 at.%, we could make a RESET programming more reliable by slower melt-quenching while maintaining a very high SET speed. The reliable RESET programming is considered as due to decreased driving force for recrystallization resulting from increased stability of the amorphous phase state.