"Obviously, this has some potentially quite serious implications, because gate leakage tunnelling through the silicon dioxide increases exponentially when the dielectric gate walls get thinner and thinner. Excessive current leakage causes an increase in power dissipation and heat output – something that the Prescott core was famous for. What you end up with is a transistor that’s never fully switched to off; instead, you’ve got millions of transistors that resemble a light bulb that only dims when you switch it off. In other words, the transistors end up becoming power inefficient."
Check it out Bit Tech.