n‐ andp‐doped GaN thin films have been epitaxially grown onc‐sapphire substrates by metal‐organic chemical‐vapor deposition in a production scale multiwafer‐rotating‐disk reactor. Theinsitudoping was performed with material having a low background carrier concentration ofn∼mid‐1016cm−3. Biscyclopentadienyl magnesium (Cp2Mg) and disilane (Si2H6) were used as the precursors for thepandndopants, Mg and Si, respectively. The effect of mole flow on material, electrical, and optical properties was studied. We observed that bothn‐ andp‐type doped GaN exhibited an excellent surface morphology, even with a high mole flow of doping precursors. After the Mg‐doped GaN was annealed in a N2ambient at ∼700 °C for 30–60 min, the highly resistive GaN was converted intop‐type GaN with a low resistance of 0.1–1.0 Ω cm. Transmission electron microscopy showed that the defect density on the annealed Mg‐doped GaN is only 4×109cm−2which is of the same order as undoped GaN (1.5×109cm−2). One of the bestp‐GaN samples has a Hall carrier concentration of 5.2×1018cm−3and a hole mobility of 20 cm2/V s, which are the best values reported in the literature to date. The photoluminescence spectra ofp‐GaN show a strong band edge at 430 nm with a full width at half‐maximum of 300 meV at room temperature.