Using surface charge analysis to characterize the radiation response of Si/SiO2 structures

We show that a surface charge analyzer (SCA) can be used to measure the total-dose radiation response of oxide-semiconductor structures noninvasively. A comparison of SCA measured radiation-induced oxide-trap charge and interface-trap densities with values from conventional metal oxide semiconductor (MOS) and mercury probe C--V measurements shows good agreement up to the highest total doses considered here (1000 krad(SiO₂)). The measured values of oxide-trap charge and interface-trap densities monotonically increase as total dose increases. Surface charge analysis has an advantage over the C--V measurement method because it does not require a direct gate contact for measurement. The SCA also does not require extra device fabrication or special test structures for measurement, circumventing the need for post-processing that could alter the charge trapping within a thermal oxide.