Random telegraph signals of tetrahedral-shaped recess field-effect transistor memory cell with a hole-trapping floating quantum dot gate

An AlGaAs/InGaAs heterojunction field-effect transistor (FET) memory cell in a tetrahedral-shaped recess (TSR) on the (111)B GaAs substrate was fabricated and investigated. The TSR-FET memory cell has a channel on the (111)A facet surfaces of the recess and a hole-trapping quantum dot (QD) as a floating gate at the bottom. Memory operations were achieved at temperatures up to 130 K, and random telegraph signals (RTSs) with a temperature dependence were observed in the retention characteristics. After our analysis of RTSs, the activation energy of hole capture and emission processes in the TSR QD were estimated to be 260 and 190 meV, respectively. (C) 2000 American Institute of Physics. [S0003-6951(00)02829-1].