Effects of post-deposition annealing in argon-oxygen-argon ambient on physical and electrical characteristics of thulium oxide passivation layer on silicon substrate

The thulium oxide (Tm2O3) passivation layer was deposited on silicon substrate via radio frequency magnetron sputtering and then subjected to different post-deposition annealing in argon-oxygen-argon ambient at 500, 600, 700, and 800°C. The grazing incidence X-ray diffraction characterisation (GIXRD) has revealed that polycrystalline Tm2O3 passivation layers were formed after the post-deposition annealing process. The elemental compositions of the investigated Tm2O3 passivation layers were characterized using energy-dispersive X-ray (EDX) spectroscopy. The result showed that the species (oxygen vacancies and oxygen interstitial) and concentration of defects in samples changed with increasing annealing temperature, which caused the Tm2O3 lattice to contract and expand as well as an increase in the direct band gap from 3.986 eV to 4.898 eV. Additionally, the thickness derived from the X-ray reflectivity (XRR) fitting result revealed that all of the annealed Tm2O3passivation layers were subjected to densification and that the SiO2 interfacial layer grew in thickness from 0.731 nm to 2.178 nm as the annealing temperature increased. The J-E characteristics of the Tm2O3 passivation layers improved as the annealing temperature increased from 500°C to 800°C, with the lowest leakage current density and highest electric breakdown field (3.03 MV/cm) being achieved at 800°C.