Domain Formation in LiNbO3 and LiTaO3 Ferroelectrics by Low-Voltage (1–3 keV) Electron Irradiation

The possibility of generating nanodomain structures in the –Z cuts of ferroelectric crystals LiNbO3 and LiTaO3 at low energies (ЕВ < 5 keV) of irradiation with primary electrons in a scanning electron microscope (SEM) is demonstrated. Calculations of the induced electrostatic fields in these crystals were performed using an energy of EB = 1 keV. The decisive effect of recharging of the near-surface contamination layer of adsorbed atoms and molecules on the processes occurring during its bombardment with electrons in a vacuum chamber of the SEM is discussed. It is shown that for each EB energy used there are extremely critical sizes of the irradiation area for the formation of domains. Experimentally, the domains were recorded in the SEM at an accelerating voltage of U = 1 kV and an electron beam current of I = 0.1 nA. The domains were identified by selective chemical etching in HF. After chemical etching, the surface was examined using an atomic force microscope (AFM) and an optical interference microscope. It was found that the irradiated areas consist of small needle-like nanodomains formed in a rather thin surface layer (~1 µm). The obtained result confirms the possibility of recording domains with an electron beam in LiNbO3 at EB = 1 keV.