Regulation of CN-related optical transitions and non-radiative capture cross-section by biaxial strain in AlN

Carbon-related 4.7 eV absorption band and small in-plane strains in AlN may have some significant effects on its application in optoelectronic devices. Based on the accurate hybrid density functional calculation, we investigate the transition energy levels, photo-transition processes, and hole capture cross-sections of C_N defect. We propose that the transition from −1 to 0 charge states of C_N defect may be responsible for the 4.7 eV absorption band in AlN. In addition, the C_N defect-related absorption and emission peaks are linearly dependent on the biaxial strain in the range of −3% to +3%, and the hole non-radiative capture rate by the C_N center at the −3% biaxial strain is only 3.65% of that at the +3% biaxial strain. This work provides an effective approach for regulating the charge carrier capture ability of the defect center and improving device performance.