1D to 1D tunneling in a dual electron waveguide device

Summary form only given. The authors report the first unambiguous observation of controlled electron tunneling between two closely spaced 1D electron waveguides. This represents a significant step toward the realization of a quantum field-effect electron directional coupler (QFED). The authors have fabricated a variety of dual electron waveguide devices with different lengths and widths on an AlGaAs/GaAs heterostructure (N/sub s/=4*0/sup 11/ cm/sup -2/ and mu =1.2*10/sup 6/ cm/sup 2//V-s at 4 K). The key feature in these devices is the 30-nm-wide middle gate fabricated using a single-pass e-beam lithography technique. Such a thin gate is required to achieve significant tunneling. A 1D to 1D regime is established when two electron waveguides are implemented. The tunneling current should be sensitive to the alignment of the subbands in the two electron waveguides. In this regime, bumps in the tunneling current are observed as a function of both side-gate voltages as the individual subbands line up between the two waveguides. This is unmistakable proof that 1D to 1D tunneling is taking place. >