Oxygen-deficiency-driven phase segregation enables enhanced hole transport in amorphous tellurium oxides

Abstract

Amorphous oxide semiconductors allow scalable electronics, yet high-mobility p-type counterparts remain rare because O-$2p$ valence bands are typically deep and spatially localized. Motivated by recent reports of unusually high hole mobilities in oxygen-deficient \ce{Se}-doped amorphous tellurium oxides ($a$-\ce{TeO${}_x$}), we investigated $a$-\ce{TeO${}_x$} with and without \ce{Se} doping using machine-learning-accelerated ab initio molecular dynamics with hybrid-functional defect calculations. We find that oxygen depletion drives nanoscale segregation into interpenetrating $a$-Te and $a$-TeO${}_2$ domains with distinct roles: Te vacancies in oxide-like/interfacial environments supply holes, while transport is mediated by percolating Te-$5p$ pathways within the $a$-Te subnetwork. Upon doping, we theoretically verify that Se preferentially incorporates into the $a$-Te domains enhancing connectivity. This preference is nontrivial without explicit modeling given that \ce{Se} shares similar electronic structure with both Te and O. We further find that reducing the oxygen content can likewise enhance hole conductivity. Finally, using amorphous SeO${}_x$, we show that domain segregation persists in other amorphous chalcogen oxides, suggesting a transferable route to achieving higher-mobility p-type amorphous oxides.

Originally submitted under the title "Atomic networks as highways for holes in oxygen-deficient amorphous oxides"

References in corpus (11)

• On-the-fly machine learning force field generation: Application to melting points
• Phase transitions of hybrid perovskites simulated by machine-learning force fields trained on-the-fly with Bayesian inference
• Low Hole Effective Mass p-type Transparent Conducting Oxides: Identification and Design Principles
• Electrostatics-based finite-size correction for first-principles point defect calculations
• Positrons in Surface Physics
• Lone Pair Effect, Structural Distortions and Potential for Superconductivity in Tl Perovskites
• Is p-type doping in TeO2 feasible?
• Native defects and $p$-type dopability in transparent $\beta$-TeO${}_2$: A first-principles study
• Exploring Intrinsic and Extrinsic $p$-type Dopability of Atomically Thin $\beta$-TeO${}_2$ from First Principles
• Investigation of Hole Dopability in Oxygen $2p$-Dominated Bands
• Machine Learning Prediction of Charged Defect Formation Energies from Crystal Structures