An Experimental Study of Carbon-Doped GaN via Solid–Gas Reaction Route and Investigation of Its Defect-Related Luminescence

Carbon-doped gallium nitride (GaN) is a very interesting material with applications in optoelectronic devices, and studies related to their defects offer insights regarding possible transitions based on the nature of the defects. A simple solid–gas reaction route has yielded carbon-doped GaN. An isolated CN defect state has been observed by spectroscopic tools (Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy) along with the CN–ON complex formation. In addition to the red shift in the fundamental absorption band, a transition band was observed at ∼3.05 eV. A complete quenching of blue luminescence (BL) related to an oxygen defect and the appearance of a carbon-related yellow luminescence (YL) is shown in strongly doped samples. The origin of this defect-related YL in C-doped GaN is attributed to the carbon-defect CN (−1 charged) level transitions confirmed by absorption energy, photoluminescence (PL) peak position, and zero-phonon line.