Electron transport properties in a GaAs/AlGaAs quantum wire grown on V-grooved GaAs substrate by metalorganic vapor phase epitaxy

A series of nonlinear conductance phenomena is investigated in the GaAs V-grooved quantum wire (QWR) field effect transistors (FETs) prepared by the flow-rate modulated epitaxy (FME) technique. These are attributed to Coulomb blockade at a subthreshold gate bias, universal conductance steps near the threshold, real space transfer under a forward gate bias and a large source-drain bias condition. Weak carrier coupling between sidewall quantum wells and QWR is responsible for the small step height of the measured universal conductance (Gm G0 = 2e2/h). Shubnikov de Haas oscillation measurements revealed that sidewall quantum wells in the V-groove quantum wire act as additional current paths and are switched or mixed with QWR depending on the gate bias conditions and device geometry. The gate-bias-dependent current path switching is found to be responsible for the large current steps and negative differential resistance (NDR) in the drain current (IDS)-gate bias (VGS) and IDS-drain bias (VDS) relationships, respectively.