U-Shaped Fermi-Level Dependence of Point-Defect Aggregation Enthalpy in Silicon
Abstract
Point defects govern the electronic and structural behavior of silicon, yet their configuration and energy depend on both the charge state and the Fermi level (EF). Using an unbiased global structure search with first-principles calculations, we screened more than 1,500 candidate structures, covering intrinsic defects and C, H, O, N, P, and B impurities in charge states from -2 to +2. The reaction enthalpy of defect aggregation depends on EF in a U shape, being strongest where the net charge transferred during the reaction vanishes and weaker toward both band edges. This U arises because complexes are more charge-neutral than their isolated constituents, so the net charge transfer changes sign across the gap. The point where this sign change occurs is set by the transition levels of the specific defects. For typical reactions, the driving force is tunable by 0.3-0.5 eV, which shifts the equilibrium complex concentration by five to eight orders of magnitude at room temperature. Our results make the Fermi level a practical lever for defect engineering in as-grown and irradiated silicon.
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BibTeX
@misc{wu2026ushaped,
title = {{U-Shaped Fermi-Level Dependence of Point-Defect Aggregation Enthalpy in Silicon}},
author = {Yin Wu and Xiao Kong and Pai Li},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10995},
eprint = {2609.10995},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10995},
}
RIS
TY - UNPB
TI - U-Shaped Fermi-Level Dependence of Point-Defect Aggregation Enthalpy in Silicon
AU - Yin Wu
AU - Xiao Kong
AU - Pai Li
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.10995
UR - https://arxiv.org/abs/2609.10995
AB - Point defects govern the electronic and structural behavior of silicon, yet their configuration and energy depend on both the charge state and the Fermi level (EF). Using an unbiased global structure search with first-principles calculations, we screened more than 1,500 candidate structures, covering intrinsic defects and C, H, O, N, P, and B impurities in charge states from -2 to +2. The reaction enthalpy of defect aggregation depends on EF in a U shape, being strongest where the net charge transferred during the reaction vanishes and weaker toward both band edges. This U arises because complexes are more charge-neutral than their isolated constituents, so the net charge transfer changes sign across the gap. The point where this sign change occurs is set by the transition levels of the specific defects. For typical reactions, the driving force is tunable by 0.3-0.5 eV, which shifts the equilibrium complex concentration by five to eight orders of magnitude at room temperature. Our results make the Fermi level a practical lever for defect engineering in as-grown and irradiated silicon.
ER -