Modulating band gap and optical activity in GaN/Zr2CO2 Heterostructure via stacking strategies for promising optoelectronic applications

ecent advances in two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides, known as MXenes, have demonstrated exceptional structural, electronic, and optical properties, making them promising candidates for energy storage, electromagnetic interference shielding, and optoelectronics. In this study, the structural, electronic, and optical properties of the GaN/Zr₂CO₂ 2D/2D heterostructure are systematically investigated across three stable stacking configurations: SSC-AA, SSC-AB, and SSC-AC. The calculations are performed using density functional theory (DFT) within the generalized gradient approximation (GGA) augmented by a Hubbard U correction (GGA+U) to accurately capture electron correlation effects. Band gaps of 0.99 eV, 1.34 eV, and 1.51 eV are obtained for SSC-AA, SSC-AB, and SSC-AC, respectively, while the negative formation energies of $-88.98$ meV/Å ², $-80.09$ meV/Å ², and $-92.24$ meV/Å ² confirm the stability of the heterostructures. Additionaly, Bader charge analysis indicates significant interlayer charge transfer, with Ga donating $+1.39e$ and N receiving $-1.37e$ in SSC-AC, the most stable configuration. Optical absorption peaks are observed near 2.8 eV for SSC-AC, suggesting its suitability for visible-range optoelectronic applications. The electron localization function (ELF) further highlights strong covalent bonding and efficient charge transfer facilitated by Zr–C and Ga–N orbital hybridization. These results provide detailed insights into the tunable electronic and optical properties of GaN/Zr₂CO₂ heterostructures , emphasizing their potential in advanced nanodevices such as photodetectors, flexible electronics, and energy storage systems.