Rare earth metal element doped g-GaN monolayer : Study of structural, electronic, magnetic, and optical properties by first-principle calculations

Using first-principle calculations, we have studied the structural, electronic, magnetic, and optical properties of the g-GaN monolayer doped with rare earth (RE) metal elements, where RE = La, Ce, Nd, Eu, Gd, and Dy. The substitution of Ga atom with RE leads to the structural deformation in g-GaN monolayer. The RE atom protrudes out from the plane of GaN monolayer. The [email protected] shows non-magnetic behavior similar to g-GaN. The induced magnetism of 1, 3, 6, 7, and 5 μB is observed with Ce, Nd, Eu, Gd, and Dy doped GaN monolayer, respectively. The band gap of g-GaN is 1.98 eV with indirect characteristics. The indirect band gap characteristics of g-GaN retains with La, Gd and Dy doping, while [email protected] shows direct band gap behavior. With Ce and Eu doping in GaN monolayer, transformation of semiconducting nature of g-GaN turns to metallic one. The decrease in the work function is observed with the RE doping in GaN monolayer reflects enhanced conductivity. For La, Nd, Gd, and [email protected], the absorption spectrum show similar nature to that of g-GaN spectra. The addition of band edge states near the Fermi of g-GaN show significant red shift in absorption spectrum for Ce and Eu doped GaN monolayers as compared with g-GaN. The absorption spectra of g-GaN extended from UV to IR with the doping of Ce and Eu atom. The static dielectric constant and refractive index of g-GaN monolayer is 1.61 and 1.57, respectively. Overall enhancement in the dielectric constants and refractive indices is seen with RE doping in GaN monolayer as compared to that of g-GaN. This study provides the basis for the development of g-GaN monolayer based optoelectronic devices.