Exploring electron energy dependencies in the formation of surface charge on ZnO crystals

This study delves into the phenomena surrounding the emergence of negative charge accumulation on the surface of zinc oxide (ZnO) crystals upon exposure to low-energy electron irradiation within the range of E = 0 ÷ 600 eV. We demonstrate the critical significance of the primary electron energy in dictating the initial processes initiated at the ZnO surface. Energy thresholds governing both the genesis and elimination of surface charge, along with the formation of oxygen vacancies on the ZnO surface, are elucidated. Our findings reveal that irradiation instigates distinct dissociative pathways contingent upon electron energy, engendering diverse physical and chemical transformations via bond dissociation, desorption, and atomic and molecular restructuring of the surface. These insights serve as pivotal groundwork towards advancing the fabrication of epitaxial films, facilitating the controlled generation of two-dimensional structures predicated on surface potential modulation.