Instability of single-electron memory at low temperatures in Al/AlOx/Al structures

A nanostructure based on a uniform one-dimensional array of ultrasmall tunnel junctions (a single-electron trap) characterized by an ability to maintain an excess charge of several electrons in an island is fabricated and investigated. Changes in the state of the trap are detected by a single-electron transistor. At the working temperature T=35 mK the storage time of a charge state is more than 8 h (which is the duration of the experiment). It is demonstrated that the possible factors limiting the lifetime of a state at temperatures below the typical temperatures for thermal activation include the influence of the random distribution and drift of the effective background charges of the metal islands, as well as the reverse influence discovered here of the transistor on the trap. As the current passing through the transistor increases, the hysteresis loop in the dependence of the charge in the trap on the control voltage narrows. It is noted that an increase in the current from 5 to 300 nA is equivalent to raising the working temperature to 250 mK. Zh. éksp. Teor. Fiz. 111, 344–357 (January 1997)