Effects of Proton Radiation on Tin Oxide: Implications for Space Electronics

This study examines the effects of 5 MeV proton irradiation, applied at fluences of 1 × 10¹¹, 1 × 10¹², 1 × 10¹³, and 1 × 10¹⁴ cm⁻², on 20 nm thick SnO_2-x thin films and field-effect transistors (FETs) with Sn-doped In₂O₃ (ITO) electrodes. In the SnO_2-x films, both carrier concentration and mobility increased steadily with rising fluences. The irradiated ITO layers displayed higher carrier concentrations but reduced mobilities compared with their pristine counterparts. Higher conductivity of the constituent films resulted in a negative shift in threshold voltage (V_th) and an enhanced drain current (I_DS) in the SnO_2-x FETs. The greater the fluence, the more pronounced these changes became. Regardless of the fluence, the on/off ratios of the FETs remained stable at ∼10⁶, indicating minimal structural damage. Moreover, the irradiation-induced changes are not temporary. When the irradiated devices are stored in air for a month or annealed at 200 °C in air for 2 h, both I_DS and V_th became more stabilized. Collectively, these results demonstrate that SnO_2-x FETs offer radiation tolerance and electrical stability, making them strong candidates for radiation-hardened electronics in space environments.