【Epitaxy Papers】Defect evolution and carrier compensation in high-growth rate MOCVD-grown β-Ga₂O₃

      Researchers from The Ohio State University have published a dissertation titled " Defect evolution and carrier compensation in high-growth rate MOCVD-grown β-Ga₂O₃ " in APL Materials.

Abstract

      Beta-phase gallium oxide (β-Ga₂O₃) grown by metal-organic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa) as the Ga precursor has recently attracted interest as an alternative to triethylgallium (TEGa). This approach enables the high growth rates required for thick drift layers in high-voltage β-Ga₂O₃ power devices. In comparison with TEGa-based growth, the impact of TMGa on deep-level defect incorporation and carrier compensation remains largely unexplored. Here, deep-level optical and thermal (transient) defect spectroscopies (DLOS and DLTS) measurements made on β-Ga₂O₃ grown over a systematically varied set of growth conditions reveal a strong effect of TMGa flow rate on the concentration of individual compensating acceptor-like defect states throughout the bandgap. The deep level spectra are significantly dominated by a heretofore unreported state at E_C-1.6 eV, whose concentration increases monotonically with TMGa flow rate. Lighted C–V measurements reveal that this new state accounts for more than 90% of the total carrier compensation. Another state at E_C-0.6 eV measured using DLTS also monotonically follows the TMGa flow rate but contributes less than 5% of the carrier compensation. The E_C-1.6 eV trap concentration tracks the carbon concentration for the growth series measured by secondary ion mass spectroscopy. This trend correlates with density functional theory predictions of carbon-related acceptor transitions near this energy. These results establish the E_C-1.6 eV level as the dominant compensating acceptor in MOCVD-grown β-Ga₂O₃ using TMGa at high growth rates, and they provide guidance for growth optimization to mitigate carrier compensation in the thick drift layers required for high-voltage β-Ga₂O₃ devices.

DOI：

https://doi.org/10.1063/5.0325051