2025/04/21 by L. Diaz, Diaz, Leopoldo, Harold P. Hjalmarson +5
Physics and Astronomy · #Computational Physics (physics.comp-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Semiconductor Quantum Structures and Devices #Semiconductor materials and interfaces #Surface and Thin Film Phenomena
paper · pdf · doi:10.48550/arxiv.2504.15459
openalex publication_date 2025/04/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Irradiation of gallium arsenide (GaAs) produces immobile vacancies and mobile interstitials. However, after decades of experimental investigation, the immobile Ga vacancy eludes observation, raising the question: Where is the Ga vacancy? Static first-principles calculations predict a Ga vacancy should be readily observed. We find that short-time dynamical evolution of primary defects is key to explaining this conundrum. Introducing a multiscale Atomistically Informed Device Engineering (AIDE) method, we discover that during the initial displacement damage, the Fermi level shifts to mid-gap producing oppositely charged vacancies and interstitials. Driven by Coulomb attraction, fast As interstitials preferentially annihilate Ga vacancies, causing their population to plummet below detectable limits before being experimentally observed. This innovative model solves the mystery of the missing Ga vacancy and reveals the importance of a multiscale approach to explore the dynamical chemical behavior in experimentally inaccessible short-time regimes.