Design and discovery of a novel Half-Heusler transparent hole conductor made of all-metallic heavy elements

TL;DR

This paper reports the theoretical prediction and experimental validation of a novel all-metallic heavy element compound, TaIrGe, as a stable, p-type transparent hole conductor with high hole mobility, expanding the search for transparent conductors beyond traditional oxide materials.

Contribution

It introduces a new methodology combining theoretical predictions and laboratory synthesis to discover transparent conductors in unexpected chemical groups, specifically all-metallic heavy element compounds.

Findings

Predicted and synthesized a stable TaIrGe compound.

Demonstrated p-type transparency with strong optical absorption at 3.36 eV.

Measured high hole mobility of 2730 cm2/Vs at room temperature.

Abstract

Metallic conductors that are optically transparent represent a rare breed of generally contraindicated physical properties that are nevertheless critically needed for application where both functionalities are crucial. Such rare materials have traditionally been searched in the general chemical neighborhood of compounds containing metal oxides, expected to be wide gap insulators that might be doped to induce conductivity.Focusing on the family of 18 valence electron ABX compounds we have searched theoretically for the ability of the compound's electronic structure to simultaneously lead to optical transparency, in parallel with the ability of its intrinsic defect structures to produce uncompensated free holes.This led to the prediction of a stable, never before synthesized TaIrGe compound made of all-metal heavy atom compound as the "best of class" from the V-IX-IV group. Laboratory synthesis then found it to be stable in the predicted crystal structure and p-type transparent conductor with measured strong direct absorption of 3.36 eV and remarkably high (albeit not predicted) hole mobility of 2730 cm2/Vs at room temperature. This methodology opens the way to future searches of transparent conductors in unexpected chemical groups.