AVS 47th International Symposium
    Electronics Tuesday Sessions
       Session EL-TuP

Paper EL-TuP5
Enhancement of Mobility with Double Delta-doped Quantum Wires by Focused Ion Beam

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: C. Lee, Honam University, Korea
Authors: S. Choi, The Aerospace Corporation
M. Leung, The Aerospace Corporation
G. Stupian, The Aerospace Corporation
N. Presser, The Aerospace Corporation
C. Lee, Honam University, Korea
Correspondent: Click to Email
100nm wide delta-doped quantum wires were fabricated by the Molecular Beam Epitaxy (MBE) and a subsequent Focused Ion Beam (FIB) milling process. Ion beam focused to submicrometer diameters offers a radical departure from the conventional fabrication routine for quantum wires such as electron beam lithography. First of all,all the double delta-doped AlGaAs/GaAs quantum well structures were grown by solid source MBE system. N-type delta-doping was made in the spacer region close to the well during the MBE growth. The structures grown are a single well with two 100nm AlGaAs spacers. 5 micrometer wide Hall bar mesas were prepared by the optical lithography and a subsequent chemical etching. Next, 100nm wide AlGaAs/GaAs quantum wires were made by a 25KeV focused Gallium ion beam at 10pA current. The excited subbands in the quantum well structures may have significant amount of carrier densities placed in the undoped region where Coulombic scattering is reduced. In addition to the delta-doping effect on the reduction of scattering, one dimensional confinement effect due to 100nm wide wire structures may contribute to the enhancement of mobility along the wire direction. As a result, three times enhancement of mobility compared to the quantum well structures were found in the low temperature Hall measurements with double delta-doped quantum wires. This type of structures and a fabrication technique may show great promise for obtaining high mobility with high densities for semiconductor devices.