High electric field transport in modulation-doped InAs self-assembled quantum dots for high-frequency applications

Modulation-doped N-AlGaAs (GaAs/InAs/GaAs/InAs)/GaAs-heterostructures with InAs-quantum dots (QDs) have been grown and investigated. Using these structures, modulation-doped field-effect transistors (MODFETs) have been fabricated and analyzed. It has been observed that they have the anomalous two-step shape in the current-voltage curve in contrast to the conventional curve with saturation. The saturation current I-dss for the second step practically does not depend on the gate bias U-G, showing that the concentration of electrons participating in the current flow becomes independent of U-G. It has been demonstrated that the QD-MODFETs present a promising type of the hot electron devices for high frequency applications. (C) 2001 American Institute of Physics.