Probing semiconductor band structures and heterojunction interface properties with ballistic carrier emission: GaAs/AlxGa1-xAs as a model system

POSTER

Abstract

Utilizing tunnel emission of ballistic electrons and holes in a tunnel transistor with a Mott-barrier collector, we have developed a method to self-consistently determine the energy gap of a semiconductor and band offsets at a semiconductor heterojunction without using a priori material parameters. As a model system, electronic band gaps of the AlGaAs alloys together with conduction and valence band offsets at the GaAs/AlGaAs (100) interfaces are measured with a resolution of several meV at 4.2 K. The direct-gap band offset ratio for the GaAs/AlGaAs (100) interface is found to be 59:41. In the indirect-gap regime, ballistic electrons from direct tunnel emissions probe the X valley in the conduction band, while those from Auger-like scattering processes in the metal base film probe the higher-lying L valley. Such selective electron collection may be explained by their different momentum distributions and parallel momentum conservation at the quasiepitaxial Al/GaAs (100) interface. We argue that the present method is in principle applicable to arbitrary type-I semiconductor heterostructures. [W. Yi. at al. Phys. Rev. B 81, 235325 (2010)]

Authors

  • Wei Yi

    • School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

  • Venkatesh Narayanamurti

    • School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

  • Hong Lu

    • Materials Department, University of California, Santa Barbara, California 93106, USA

  • Michael A. Scarpulla

    • Materials Department, University of California, Santa Barbara, California 93106, USA

  • Arthur Gossard

    • Materials Department, University of California, Santa Barbara, California 93106, USA
    • Materials Department, University of California, Santa Barbara
    • University of California, Santa Barbara