Neutron radiation effects on mos Id-Vd Characteristics

Hi,

I am working on the neutron radiation effects on mosfet like ELT, Hgate and standard mosfet devices.

I have pre and post characterization results for Id-Vd curve. Some of them shows increase in drain current after radiation where as some shows decrease in drain current after. Does anybody knows reason for that?



FYI, I haven't done Id-Vg so not able to measure leakage current or threshold shift in devices and have no idea how I can present effects of neutron on devices.

Any help and suggestions are welcome.

Neutron irradiation causes mostly displacement damage.
There will be a minuscule amount of knock-offs that induce
some charging of oxides but it is not significant. The damage
increases recombination and lowers lifetime. Body conduction
effects that are enhanced by LBJT features will reduce,
but junction leakage (generation / recombination currents)
is liable to run up.

Most modern CMOS processes are so highly doped in channel
region (S/D, fuggedaboudit) that you'd need a very high dose
(fluence) to see anything against background NA/ND.

In general we consider the explicit MOS device to be neutron
insensitive, but this does not extend to the parasitic (esp. BJT)
elements. Anything that operates on a minority carrier
principle is going to have displacement damage sensitivity.

I don't see enough consistency to assign any drift to the FET;
in the second plot you end up right where you started. More
sample size (at least three, per step, so you can take a vote)
moght help you.

But I think you're looking for an effect that the community
has long since found nonexistent. The geometric permutations
you're looking at, are employed against ionizing radiation.
Neutrons are not.