Structural, electrical, and thermal characterization of homoepitaxial close-injection showerhead metalorganic chemical vapor deposition β-Ga2O3 enhancement-mode recessed-gate MOSFETs

A systematic investigation was performed on the impact of the β-gallium oxide (Ga2O3) epitaxial buffer layer thickness grown by close-injection showerhead metalorganic chemical vapor deposition (CIS-MOCVD) on the film’s structural, electrical, and thermal characteristics. Varying thicknesses of unintentionally doped β-Ga2O3 epitaxial layers were grown by CIS-MOCVD on Fe-doped (010) β-Ga2O3 substrates, followed by a 10 nm β-Ga2O3 Si-doped layer with a Si concentration of 1019 cm−3. Gate-recessed lateral metal–oxide–semiconductor field-effect transistors were fabricated with these epilayer films. The device characteristics and secondary ion mass spectroscopy results highlighted the need for precise Si doping within the channel, as well as minimizing the Si accumulation at the epilayer-substrate interface for proper device operation. The results from positron annihilation spectroscopy did not indicate a strong correlation between the epilayer thickness and Ga-related vacancies, and the thermal conductivities of the epilayers were consistent with increasing thickness as shown in the device-level frequency-domain thermoreflectance analysis.