Principal Investigator :

Lionel Calmels ()
CEMES (MEM et Sinano)

Type of project : Collaborative Project

Partner team(s) :

LPCNO (Nanotech)

Date (start/end) : 2017 - 2019

     

       

Abstract

Ge ₂ Sb ₂ Te ₅ alloys show resistivity variations of several orders of magnitude depending on their local atomic structure which can be manipulated through thermal treatment. For this reason, these materials are foreseen by STMicroelectronics, a member of the NEXT Club, to be used in Phase Change Memory devices at the 28 nm node and below. These simple two terminal non-volatile devices could be read by probing the resistivity of few nanometer thick layers and written and erased by controlling the current flow through the layer. Once this said, little is known on the correlation between the local atomic structure of the possible different phases (eventually doped), and their electrical conductivity. It is the goal of this project to shed light on these correlations, a prerequisite condition to device optimization. This correlation will be analyzed by comparing, for samples that will be heated and cooled under different and well controlled conditions, the atomic/chemical structure measured by TEM (HREM, HAADF, EELS…) and X-ray diffraction/diffusion, the electrical conductivity measured by local probes and at the device level and the atomic structure and transport properties as predicted from first principles calculations. Pure and doped Ge ₂ Sb ₂ Te ₅ thin layers will be provided by STMicroelectronics as well as various characterizations at the device level.

Mixing state-of-the-art theory and experiments, willing to understand intriguing structure/properties relationships at the nanoscale and make the best use of this knowledge to fabricate better devices, this project aims at demonstrating the added value NEXT can offer to its industrial partners.