Irradiation effects of 6 MeV electron on electrical properties of Al/Al2O3/n-Si MOS capacitors

Abstract

The influence of 6MeV electron irradiation on the electrical properties of Al/Al2O3/n-Si metal–oxide–semiconductor (MOS) capacitors has been investigated. Using rf magnetron sputtering deposition technique, Al/Al2O3/n-Si MOS capacitors were fabricated and such twelve capacitors were divided into four groups. The first group of MOS capacitors was not irradiated with 6MeV electrons and treated as virgin. The second group, third group and fourth group of MOS capacitors were irradiated with 6MeV electrons at 10kGy, 20kGy, and 30kGy doses, respectively, keeping the dose rate ∼1kGy/min. The variations in crystallinity of the virgin and irradiated MOS capacitors have been compared from GIXRD (Grazing Incidence X-ray Diffraction) spectra. Thickness and in-depth elemental distributions of individual layers were performed using Secondary Ion Mass Spectrometry (SIMS). The device parameters like flat band voltage (VFB) and interface trap density (Dit) of virgin and irradiated MOS capacitors have been calculated from C vs V and G/ω vs V curve, respectively. The electrical properties of the capacitors were investigated from the tan δ vs V graph. The device parameters were estimated using C–V and G/ω–V measurements. Poole–Frenkel coefficient (βPF) of the MOS capacitors was determined from leakage current (I)–voltage (V) measurement. The leakage current mechanism was proposed from the βPF value.