Epitaxial growth and deep level characterization of GaAs₁₋xPx

[abstract missing

Tunable nonlinear current-voltage characteristics of three-terminal ballistic nanojunctions

The current-voltage (I-V) characteristics of three-terminal ballistic junctions (TBJs) fabricated from high-electron-mobility GaInAs/InP quantum-well structures are measured in the six-terminal configuration. These characteristics show strong nonlinear, diode-like behavior, in agreement with recent theoretical calculations. Furthermore, the I-V characteristics are tunable by the voltage applied directly to one branch of the TBJs acting as a gate. An additional tuning of the characteristics of the TBJ devices can be performed using an in-plane side gate. All the presented characteristics are measured at room temperature, which makes TBJ devices promising for future nanoelectronic applications. (C) 2003 American Institute of Physics

Resonant tunneling via donor X states in the AlAs barrier and binding energies of donors bound to X-XY and X-Z valleys

Magnetotransport in GaAs/AlAs/GaAs single-barrier heterostructures, incorporating unintentional donors in the barrier, is studied. Resonant tunneling is observed through the quasiconfined states in the AlAs layer which originate from the X-XY and X-Z conduction-band minima and through two distinct states of the donors bound to the X-XY and X-Z valleys. This allowes us to determine directly the binding energies of X-XY- and X-Z-related donors at the center of a 5-nm AlAs barrier as E-B(X-XY)approximate to70 meV and E-B(X-Z)approximate to50 meV, respectively. Furthermore, we observe an additional oscillatory fine structure of the donor resonances which we attribute to a difference in the binding energies of donors located at different position in the AlAs layer

Three-terminal ballistic junctions: new building blocks for functional devices in nanoelectronics

A three-terminal ballistic junction (TBJ) is a device in which three quantum point contacts are coupled via a ballistic region. Previous studies have shown that the TBJs exhibit a novel electrical property which has potential applications in nanoelectronics. Here, based on our recent theoretical and experimental investigations, we will demonstrate that various nanoelectronic devices can be fabricated using the TBJs as building blocks. In particular, the results of our recent design, fabrication, modeling and measurements of TBJ diodes and transistors, TBJ frequency multipliers, and TBJ logic gates will be presented and discusse

A novel device principle for nanoelectronics

We report on the results of our recent theoretical and experimental investigations of a novel, room temperature electrical property of three-terminal ballistic junctions (TBJs). For a symmetric TBJ device, it is found that when finite voltages V-1 and V-r are applied in push-pull fashion, with V-1 = V and V-r = - V. to the left and right branches, the voltage output V-c from the central branch will always be negative. This property is in strong contrast to a symmetric three-terminal device made from conventional diffusive conductors, for which Ohm's law predicts a constant zero output of V-c for all V-1 - V-c.This novel characteristic appears even when the device symmetry is broken, provided that V is greater than the threshold. It is also shown that the TBJ devices show a good parabolic behavior for V-c vs. V in a large range of voltages V

Unidirectional electron flow in a nanometer-scale semiconductor channel: A self-switching device

By tailoring the boundary of a narrow semiconductor channel to break its symmetry, we have realized a type of nanometer-scale nonlinear device, which we refer to as self-switching device (SSD). An applied voltage V not only changes the potential profile along the channel direction, but also either widens or narrows the effective channel depending on the sign of V. This results in a diode-like characteristic but without the use of any doping junction or barrier structure. The turn-on voltage can also be widely tuned from virtually zero to more than 10 V, by simply adjusting the channel width. The planar and two-terminal structure of the SSD also allows SSD-based circuits to be realized by only one step of lithography. (C) 2003 American Institute of Physics

Surviving conduction symmetries in non-linear response

In linear response, the electric conductance of mesoscopic, two-terminal devices is symmetric with respect to the direction of an external magnetic field. The conductance symmetry, in general, breaks down in the non-linear regime of transport. Here we consider semiconductor quantum dots and show certain symmetries survive in the non-linear conductance with respect to the bias voltage and magnetic field that can be measured. (C) 2004 Published by Elsevier Ltd