Single-charge storage effects and transport properties in n-AlGaAs/GaAs heterojunction transistors with a constricted-channel induced by focused-ion-beam implantation

We investigated single-charge storage effects and transport properties of a constricted channel induced by Ga-focused-ion-beam (Ga-FIB) implantation in an n-AlGaAs/GaAs heterojunction field effect transistor. In our device, multiple localized sites are embedded as carrier trapping centers by using high-dose (> 1015 ions/cm2) implantation in the vicinity of a quasi- one-dimensional channel. The device demonstrates a quantized threshold voltage shift (∼ 20 mV) at room temperature, which is due to the Coulomb interaction of tunneling and to storage of electrons in discrete trap levels. The memory effect is very stable and nonvolatile for more than an hour. This simple technique will be utilized for fabricating memory and unique quantum nanostructure devices.