2025/11/26 by Leopoldo Diaz, Harold P. Hjalmarson, Jesse J. Lutz +1 · 1 voice
Engineering · Physics and Astronomy · #Semiconductor Quantum Structures and Devices #Silicon and Solar Cell Technologies #solar cell performance optimization
paper · doi:10.1103/scn4-2wmv
openalex publication_date 2025/11/26 · openalex created_date 2025/12/11 · openalex updated_date 2026/08/01
Irradiation of gallium arsenide (GaAs) produces immobile vacancies and mobile interstitials. Yet, after decades of experimental investigation, the immobile Ga vacancy continues to evade detection, 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 the key to explaining this conundrum. Using a dynamical multiscale atomistically informed device engineering (AIDE) method, we discover that during the initial displacement damage, the Ga vacancy (3-/2-) defect level pins the Fermi level near the midgap, producing oppositely charged vacancies and interstitials. Driven by Coulomb attraction, fast As interstitials preferentially annihilate Ga vacancies. The Ga vacancy population plummets below detectable limits-and the now unpinned Fermi level recovers-before being experimentally observed. This dynamical 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.