Characterization of extended defect evolution in 1.2–12 μm thick homoepitaxial (010) β-Ga2O3 grown by close-injection showerhead metal-organic chemical vapor deposition

Homoepitaxial Si-doped (010) β-Ga2O3 epitaxial layers with thicknesses ranging from 1.2 to 12 μm were grown simultaneously via close-injection showerhead metal-organic chemical vapor deposition on both Czochralski and edge-defined, film-fed grown (010) β-Ga2O3:Fe substrates. Structural characterization was performed via x-ray diffraction [full-width at half maxima of 21–72 arcsec depending on epilayer thickness and substrate, measured from the symmetric (020) reflection], x-ray topography, Raman spectroscopy, cathodoluminescence spectroscopy, and transmission electron microscopy. Surface characterization was performed via atomic force microscope (AFM) and Nomarski imaging, and electrical characterization was performed via electron paramagnetic resonance spectroscopy and Hall effect measurements. In addition, thermal conductivity was measured via steady-state thermoreflectance. AFM imaging revealed a number of extended defects forming in the epilayer, and transmission electron microscopy imaging detailed a V-shaped pit defect formed by misoriented twin defects likely originating from a defect at or near the substrate surface. The Hall effect data (NS = 2.81–3.1 × 1017 cm−3 and μH = 81.5–103.5 cm2/V s), surface roughness (1.78–4.25 nm rms), and thermal conductivity measurements (19.3–19.8 W/m K) yielded comparable results among all samples, independent of epilayer thickness. These results suggested that even thicker, high quality epitaxial (010) β-Ga2O3 could be grown via this technique, provided that the development of the observed extended defects can be mitigated.