Session:

Layered electrides are ionic solids comprised of weakly-interacting atomic layers in which the conducting 2D electrons are confined to the interstitial region between the atomic planes, or on their surfaces when exfoliated to form 2D electrides. Because the conducting electrons are physically separated from the lattice, layered electrides display high conductivity, low electron-phonon (el-ph) coupling, and low work function. As a result, they are promising material candidates for applications in transparent conductors, electron emitters, ohmic contacts to 2D semiconductors, and interconnects.

In this talk, we present our first-principles study exploring the transport and electron-phonon scattering characteristics of seven layered electrides of the form M₂X, where M is an alkaline earth metal (M = Ca, Sr, Ba) and X is a pnictogen (X = N, P, As, Sb). Our density functional theory calculations reveal that Sr₂N and Ca₂N have the lowest electrical resistivity and el-ph scattering rates among this group of electrides. To better understand what controls these properties, we analyze and compare their scattering phase space, average el-ph coupling, distribution of modes, average velocity, and mean-free-path for backscattering. Interestingly, while Ca₂N shows some of the lowest el-ph collision rates, resulting from its small scattering phase space, it has the largest el-ph interaction strength. Repeating these calculations for the metals Al, Au, and Cu reveals that their el-ph coupling can be an order of magnitude greater than the electrides. The decoupling of the conducting 2D electrons from the lattice in layered electrides, leading to weak el-ph interaction, suggests that these materials may be promising interconnects in nanoelectronic circuits.

Co-Author(s): Vahid Askarpour (Dalhousie University)

Jesse Maassen

Dalhousie University

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