The Effects of Electron-Beam-Radiation-Induced Damage on Single-Crystal Silicon Devices with SiO2 Surface Passivation in a Nitrogen Atmosphere

In energy conversion semiconductor devices, radiation damage is directly related to the long-term stability of β-voltaic batteries. In this study, single-crystalline silicon P+NN+ devices and P+-silicon materials with SiO2 surface passivation were irradiated using a ~70 keV accelerator electron beam in a nitrogen atmosphere for 2 min, 10 min, 1 h, 6 h, and 12 h. The tritium-voltaic output decreased rapidly within the first 2 min of electron beam irradiation and then decayed slowly. After 1 h of irradiation, both the output short-circuit current (Isc) and open-circuit voltage (Voc) remained stable. The effects of the damage were analyzed using typical samples irradiated for 1 h. Neutron reflectometry (NR) was employed as the primary characterization method, while X-ray photoelectron spectroscopy (XPS)—combined with Ar+ etching—and secondary ion mass spectrometry (SIMS) were used to verify radiation-induced structural changes at the SiO2 surface and SiO2/Si interface. It was found that nitrogen atoms from the atmosphere penetrated the SiO2 layer to a depth of approximately 5–10 nm, forming a non-stoichiometric SiON structure, without further diffusion into deeper layers. Irradiation significantly increased the thickness of the SiO2/Si interface transition layer to about 14–18.5 nm, and the SiO2 structure within this layer became relatively loose. It can be inferred that tritium-voltaic batteries using SiO2-surface-passivated single-crystalline silicon P+NN+ devices as energy-conversion units and packaged in a nitrogen atmosphere can stably provide power for 10 years, with an Isc reduction of no more than 12% and a Voc reduction of no more than 6%, excluding the spontaneous decay of tritium.