Tuesday, January 2, 2018

Single Atomic Layer Ferroelectric on Silicon by PVD ZrO2


A team of mainly US based researchers from (Yale, MIT, Université de Genève and Globalfoundries) have been able to scale down ferroelectric ZrO2 to only one atomic layer on silicon using PVD. This record breaking thin monolayer ferroelectric allows for more aggressively scaled devices than bulk ferroelectrics as compared to the most current 5–10 nm thick layers based on e.g. Si:HfO2 and HfZrOx. 

They found that:
  • single atomic layer ZrO2 exhibits ferroelectric switching behavior when grown with an atomically abrupt interface on silicon
  • ZrO2 gate stack demonstrate that a reversible polarization of the ZrO2 interface structure couples to the carriers in the silicon.
Single Atomic Layer Ferroelectric on Silicon
Mehmet Dogan, Stéphanie Fernandez-Peña, Lior Kornblum, Yichen Jia, Divine P. Kumah, James W. Reiner, Zoran Krivokapic, Alexie M. Kolpak, Sohrab Ismail-Beigi, Charles H. Ahn, and Frederick J. Walker

Nano Lett., Article ASAP, DOI:10.1021/acs.nanolett.7b03988

Abstract: A single atomic layer of ZrO2 exhibits ferroelectric switching behavior when grown with an atomically abrupt interface on silicon. Hysteresis in capacitance–voltage measurements of a ZrO2 gate stack demonstrate that a reversible polarization of the ZrO2 interface structure couples to the carriers in the silicon. First-principles computations confirm the existence of multiple stable polarization states and the energy shift in the semiconductor electron states that result from switching between these states. This monolayer ferroelectric represents a new class of materials for achieving devices that transcend conventional complementary metal oxide semiconductor (CMOS) technology. Significantly, a single atomic layer ferroelectric allows for more aggressively scaled devices than bulk ferroelectrics, which currently need to be thicker than 5–10 nm to exhibit significant hysteretic behavior (Park, et al. Adv. Mater. 2015, 27, 1811).

Reprinted with permission from (Single Atomic Layer Ferroelectric on Silicon, M. Dogan et al, Nano Letters, Dec 2017). Copyright (2018) American Chemical Society.

High‐resolution STEM image and EDX intensity profiles of Si, Al and Zr. The Supporting Information is available free of charge on the ACS Publications website at "Single Atomic Layer Ferroelectric on Silicon" https://figshare.com/collections/Single_Atomic_Layer_Ferroelectric_on_Silicon/3961401