Dissipative tunneling in two-state systems at the Si/${\mathrm{SiO}}_2$ interface

We have observed two-state systems (TSSs) in electrically stressed metal-oxide-silicon field-effect transistors, by studying random telegraph signals at low temperatures. The TSSs are related to defects close to the Si/${\mathrm{SiO}}_2$ interface. The asymmetry energy ɛ is linear in gate voltage, permitting for the first time measurement of the dissipative tunneling rate as a function of ɛ independently of magnetic field. The electron coupling strength α lies in the range ${10}^{\mathrm{-}3}$ to ${10}^{\mathrm{-}2}$, allowing comparison with the standard theory in the previously unexplored regime of weak coupling.