INDUCED STRUCTURAL STABILITY AND ELECTRONIC BEHAVIOR OF GERMANENE LAYER WITH ADSORBED GALLIUM AND ARSENIC ADATOMS: A FIRST-PRINCIPLES STUDY

Abstract

Using first-principles density functional theory within Quantum ESPRESSO, we investigate the adsorption behavior of Gallium (Ga), Arsenic (As), and a vertical GaAs cluster on a 4×4 buckled germanene monolayer. Three high-symmetry sites—hollow (H), bridge (B), and top (T)—are analyzed using the Perdew-Wang 91 GGA and Vanderbilt ultrasoft pseudopotentials. Structural optimization reveals the hollow site as the thermodynamic ground state, offering multi-center coordination that minimizes strain. Pristine germanene is a gapless semimetal with a Dirac cone at the K-point. Functionalization at the hollow site modifies its electronic properties: As chemisorption breaks sublattice symmetry, opening a band gap of 0.42 eV, while Ga induces a wider gap of 0.78 eV. The GaAs co-adsorbed cluster achieves the most pronounced effect, producing a transport gap of 1.26 eV through dual covalent stabilization. Density of states and charge density analyses confirm these transitions are driven by robust p–p orbital hybridizations (As-pz, Ga-pz, Ge-pz). Spin-polarized calculations show perfect symmetry between channels, ensuring all configurations remain non-magnetic (μ_tot = 0 μB). These results establish germanene functionalized with Ga/As as a stable, tunable platform for high-mobility 2D/III-V nanoelectronics, photovoltaic, and optoelectronic applications.