Competitive surface adsorption governs unintentional Si incorporation in MOCVD-grown β -Ga 2 O 3 (001) homoepilayers

Abstract Precise control over residual silicon (Si) impurities in unintentionally doped (UID) β -Ga 2 O 3 epilayers is crucial for high-power devices, yet remains challenging due to complex mechanisms governing Si incorporation. In this work, we examine the effects of VI/III ratio and growth rate (GR) on residual Si impurities and net donor concentrations in (001)-oriented β -Ga 2 O 3 UID homoepilayers grown by metal organic chemical vapor deposition (MOCVD). The unintentionally incorporated Si concentration is found to be suppressed below 10 16 cm −3 , which is at the secondary ion mass spectrometry instrument’s detection limit, resulting in a net donor concentration of 4.73 × 10 15 cm −3 by increasing the GR to 1.08 μ m h −1 . Although carbon and hydrogen impurities are sensitive to VI/III mole ratios, they exert negligible impact on Si incorporation efficiency. Within a Langmuir adsorption framework, Si incorporation is governed by a competitive surface adsorption process between Ga and Si species on the growing surface, and a universal quantitative correlation between Si incorporation and GR holds true for a broad range of MOCVD-grown β -Ga 2 O 3 UID layers across different orientations and MOCVD reactor systems.