MgO (1 0 0) as an affordable support for heteroepitaxial growth of high-quality β-Ga2O3 thin films and related highly-sensitive solar-blind UV photodetectors

•MgO (100) is affordable substrate for hetero-epitaxial growth of high-quality β-Ga2O3 (100) films.•Optimal O2 pressure is 7 Pa, resulting in films with great atomic ordering and roughness of 0.216 nm.•The films initialize with a γ-Ga2O3 transition layer and consist of 8–12 nm-wide columnar nanodomains.•AC-TEM reveals occurrence and preferred location of oxygen-vacancies at domain walls.•Derivative SBUVPDs exhibit superior performance of Idark = 0.6 pA, R = 191 A/W, and D = 3.08 × 1015 Jones.