RANDOM TELEGRAPH SIGNALS FROM LIQUID-HELIUM TO ROOM-TEMPERATURE

The noise in unstressed MOSFETs at temperatures as low as 1.2 K is pro duced mainly by electron-trapping defects, as it is at room temperatur e. However, the defects active at low temperatures lie closer to the S i/SiO2 interface, showing a preference for particular effective depths (2.2 and 5.5 angstrom) into the oxide, and they influence the conduct ance mainly by scattering rather than number density modulation. After electrical stress many more defects a-re active, and their interactio n with the conduction electrons is very complex. A new type of defect is detected amongst them which acts not as an electron trap but as a t wo-state system, producing random telegraph signals whose time constan ts show dramatic resonances as a function of gate voltage.