Single electron charging at temperatures above 4 K in ultrasmall lateral quantum dots patterned on shallow GaAs/AlGaAs heterostructures

Abstract

We demonstrate single electron charging in fully controllable nanoscale quantum devices at temperatures above 4 K. Hitherto, single electron devices operating at ‘‘high’’ temperatures have been two-terminal, having no control electrode, whereas fully tunable structures such as quantum dots have only shown charging effects at temperatures of 4 K or less. We have fabricated ultrasmall quantum dots on modulation doped heterostructures where the two-dimensional electron gas is less than 30 nm from the surface. Dots with lithographic diameter 150 nm show Coulomb oscillations up to temperatures of 7 K. Higher temperature operation allows potential applications to be considered without the need, for example, of a dilution fridge.