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GaN samples are implanted with Be and F and annealed in different conditions to activate the Be_Gaacceptors. Photoluminescence spectra are studied to recognize the defects. The UVL_Beband with a maximum at 3.38 eV and the YL_Beband with a maximum at 2.15 eV are observed and associated with Be. The sequential implantation of Be and F ions into GaN at 600 °C reduces the concentration of nitrogen vacancies (V_N), as evidenced by the lack of the green luminescence band associated with the isolated nitrogen vacancy. First‐principles calculations are employed to find parameters of defects that can form after implantation. 

A systematic photoluminescence study of Be‐doped GaN grown by metal‐organic chemical vapor deposition is presented. All Be‐doped samples show the ultraviolet luminescence (UVL_Be) band with a maximum at 3.38 eV and the yellow luminescence (YL_Be) band with a maximum at ≈2.15 eV in GaN:Be having various concentrations of Be. The UVL_Beband is attributed to the shallow state of the Be_Gaacceptor with a delocalized hole. The YL_Beband is caused by a Be‐related defect, possibly the polaronic state of the Be_Gaacceptor with the charge transition level at 0.3 eV above the valence band. This broad band exhibits unusual properties. In particular, it always shows two steps in its thermal quenching. The second step atT ≈ 200 K is attributed to the emission of holes from the 0.3 eV level to the conduction band. The origin of the first step remains unexplained. 

The dissociation of the C_NH_icomplex in GaN is studied in detail using photoluminescence measurements and first‐principles calculations. The blue luminescence (BL2) band with a maximum at 3.0 eV is caused by electron transitions from an excited state located at 0.02 eV below the conduction band to the ground state of the C_NH_idonor with the 0/+ level 0.15 eV above the valence band. The dissociation releases hydrogen atom, and the remaining C_Ndefect with the −/0 state at 0.92 eV above the valence band is responsible for the yellow band (YL1) with a maximum at about 2.2 eV. The dissociation of the C_NH_icomplex can be caused by the photoinduced defect reaction mechanism under UV illumination at low temperature (≈20 K), leading to the bleaching of the BL2 band and simultaneous rise in the YL1 band. The bleaching is reversible. Alternatively, the complex dissociates after annealing at temperatures above 600 °C. The activation energy of this process (3–4 eV, depending on the annealing geometry) corresponds to the removal of hydrogen from the sample and not to the dissociation of the complex itself.