In Situ Study of Radiation Stability and Associated Conduction Mechanisms of Nb-Doped TiO2/p-Si Heterojunction Diode Under Swift Heavy Ion Irradiation

In situ current-voltage characteristics of Nb-doped TiO
₂
/p-Si-based heterojunction diode have been studied under dense electronic excitations of 84-MeV Si
⁶⁺
ions. The diode parameters such as ideality factor (η), barrier height (φ
_B
), reverse saturation current (J
_s
), and series resistance (R
_s
) are found to be a strong function of ion irradiation fluence. The observed anomalies of fluence dependence of barrier height and ideality factor are explained in terms of irradiation-induced created defects complexes, modification of interface states and structural properties of Nb-doped TiO
₂
(NTO) layer. Several mechanisms such as barrier height inhomogeneity, donor defects-induced enchantment in n-NTO layer conductivity, and various current conduction mechanisms involved at different voltage ranges are discussed as a function of fluence with the help of constructed energy band diagram. Such in situ studies on n-NTO/p-Si heterojunction diode under radiation harsh environment are very appropriate for the better understanding of heterojunction interface properties and make it suitable for use in aerospace industry and nuclear reactors.