Non-Kramers iron S = 2 ions in β-Ga2O3 crystals: High-frequency low-temperature EPR study

Abstract

Using high-frequency electron paramagnetic resonance (EPR), we have observed non-Kramers ions with giant fine structure splitting of the order of 100 GHz in n-type β-Ga2O3 crystals. These EPR spectra were assigned to Fe2+ ions 5 D (3 d 6) with S = 2. This interpretation was supported by experiments on Fermi level displacement induced by high-energy electron irradiation and photoexcitation of irradiated samples with 405-nm laser light. The values and signs of the basic parameters of the spin Hamiltonian for ions, namely Cr3+ ( S = 3/2) and Fe3+ ( S = 5/2), were identified, and the order of their spin levels was established.