Comparison of Charge Pumping and $1/f$ Noise in Irradiated Ge pMOSFETs

Irradiated Ge pMOSFETs have been characterized via charge pumping (
I
_CP
) and 1/
f
noise. The noise increases much more with irradiation than does
I
_CP
for devices with eight Si monolayers at the interface, while devices with five Si monolayers and lower halo implantation dose exhibit comparable increases in noise and
I
_CP
with irradiation. These results suggest that border traps in the HfO
₂
affect the noise more than interface traps, and that devices with eight Si monolayers have a higher border-trap density than devices with five Si monolayers. Noise measurements as a function of gate voltage show that the border trap density increases significantly toward the Ge valence band edge, while three-level charge pumping reveals an interface trap density that increases slightly toward midgap.