Radiation effects on electrical conduction properties in MIScapacitor

摘要

Effects of radiation on MOS structure were investigated bymeasurements of current vs. bias voltage (I-V) characteristics. It isshown that the I-V characteristics are dependent on the totalirradiation doses. When the gate is negatively biased, the currentthrough the oxide is found to be ohmic current at a lower field andspace-charge-limiting current at a higher field. The dose dependence ofthe ohmic current can be explained by the effect of positive spacecharge induced in the oxide layer irradiation. When the gate ispositively biased, the current is found to be ohmic current at a lowerfield and Schottky current at a higher field. The voltage at which thetransition from the ohmic current to the Schottky current occurs isfound to decrease with increasing irradiation doses. This tendency canbe explained in terms of the effective potential barrier lowering due tothe trap charges at the Si-SiO₂ interface