Defect-specific compensation and redistribution of Si in GaAs:Si structures resolved at subnanometer scale

Abstract

Although the behavior of silicon (Si) in gallium arsenide (GaAs) has been extensively studied, a comprehensive understanding of compensation mechanisms and defect dynamics remains an active area of research. Moreover, a methodological gap persists between atomic-scale defect identification and quantitative depth profiling across technologically relevant device architectures. In this study, we investigated a GaAs/GaAs:Si/GaAs multilayer structure grown by metalorganic vapor phase epitaxy, along with calibration samples of varying silicon concentrations, using a combined approach of Ultra Low Impact Energy Secondary Ion Mass Spectrometry (SIMS) and Electrochemical Capacitance–Voltage profiling. To our knowledge, this work provides the first quantitative depth profiles of individual silicon-related defects—including SiGa, SiAs, SiGa–SiAs pairs, and SiGaVGa complexes—with subnanometer resolution. Polyatomic species specific to these defects were identified, enabling SIMS signals to be linked directly to carrier concentration. A calibration strategy integrating a material-specific defect model with experimental profiles was developed, unlocking quantification of defect distributions solely based on SIMS data. Post-growth annealing (800–1000 °C) revealed defects, redistribution, and diffusion behavior, allowing the extraction of diffusion parameters for SiGa and Si pairs species. Our findings establish a quantitative framework for disentangling the individual contributions of silicon-based defects to compensation effects in GaAs:Si.