Synthesis of Highly Stable Hafnium Diselenide Thin Films via a Hybrid Deposition Method with an Amorphous Boron Nitride Passivation Layer

Abstract

Transition metal dichalcogenides (TMDs) are two-dimensional materials with transition metal and chalcogen atomic layers, offering properties like a bandgap and high carrier mobility for electronic devices. HfSe2, theoretically predicted to exhibit the highest electron mobility at room temperature, shows lower experimental mobility due to surface oxidation caused by high defect density. To address these issues, HfSe2 thin films were synthesized using a hybrid deposition method that combines laser ablation for Hf and thermal evaporation for Se, achieving precise flux control. Raman and XRD analyses confirmed high crystallinity and uniformity, while electrical measurements showed lower resistivity than single crystals. Se-rich samples exhibited reduced sheet resistance, attributed to minimized Se deficiency. Amorphous boron nitride (a-BN) passivation prevented oxidation, improving both structural stability and electrical performance. These findings demonstrate the potential of HfSe2 as a next-generation 2D semiconductor.