Charging Effects in Al-SiO2-p-Si Structures After Low-Energy Electron Beam Irradiation

The effect of electron beam irradiation on trap charging and interface defect generation in Al/SiO2/Si structures was investigated by high-frequency capacitance–voltage measurements. Irradiation was carried out with two beam energies, at which the electron penetration depth was smaller and larger than the SiO2 thickness. The effect of applied bias, which changes the electric field inside the SiO2 film and the Si surface potential, on both the interface defect generation under the electron beam irradiation and their annealing was revealed. This showed that excess electrons generated by an e-beam play an important role in the interface defect formation. It was found that interface trap relaxation can occur even at room temperature, likely by electron tunneling from Si or hole tunneling from SiO2. The relaxation of positive bulk charge occurs at temperatures higher than 400 K via thermally stimulated carrier escape from traps. The activation energy for this process was estimated as 0.35–0.4 eV.