High-energy radiation effects on subthreshold characteristics, transconductance and mobility of n-channel MOSFETs

摘要

The influence of 8 MeV electrons on the threshold voltage (V_(TH)) transconductance (g_m) and mobility (μ) of n-channel depletion metal-oxide semiconductor field-effect transistors (MOSFETs) irradiated at gate bias, V_(GS) = +2,0 and -2 V, has been studied in the dose range of 0.5-31 kGy. The measurements performed after irradiation showed considerable decrease in V_(TH), g_m and μ. The densities of interface trapped charge (ΔN_(it)) and oxide trapped charge (ΔN_(ot)) for irradiated devices have been estimated from the subthreshold measurements. It has been found that ΔN_(ot) is higher than ΔN_(it). The mobility of carriers (μ) in the n-channel was estimated from the peak transconductance (g_(mPeak)) and it was found that μ decreased by around 68.5-73.5% after exposure to the total dose of 31 kGy. Mobility degradation coefficients due to interface traps (α_(it)) and oxide trapped charge (α_(ot)) were estimated and it was found that the mobility degradation was mainly due to _(it) and the effect of ΔN_(ot) was negligible.