Memorie non volatili a semiconduttore su scala nanometrica basate sul cambiamento di fase: modellistica da principi primi della struttura geometrica ed elettronica del materiale a cambiamento di fase.

Phase Change Memories (PCM) have been introduced in the late 60s and are based on the phase transition of a chalcogenide alloy, typically Ge2Sb2Te5 (GST). The crystalline and amorphous phases involved in the transition, present well differentiated electric resistivity values and optical properties. Nowadays, the PCM appear as the most promising solution for data storage, not only for the market of non volatile memories in the post-Flash era, but also as future universal memories able to cover both DRAM and SRAM applications. The structure of GST, in the two phases of most relevant technological interest, has not been uniquely defined yet. The present work is thus aimed at modelling the relationships between geometrical and electronic structure of the GST from first principles. This study is part of a joined project 1 between Politecnico di Milano, Dipartimento di Elettronica e Informazione, and CNR-ISTM, funded by Fondazione CARIPLO, and of a PRIN project 2 involving qualified researchers in the field of non-volatile technologies and exploiting the support by STMicroelectronics which will realize the integrated structures needed to develop the projected activities.