Nanostructures for Very High Frequency Electronics

Abstract

Abstract : The study of a new class of mesoscopic high frequency semi-conductor devices based on resonant tunneling in staggered-bandgap heterostructures with III-V semi-conductor ternary alloys such as AlGaSb and InAsSb has been made. In staggered-bandgap heterostructures even electron energy levels and their wave functions cannot be determined in the framework of one band model. The multiband model calculation predicts four quasi-discreet levels in the quantum well of AlGaSb/InAs/AlGaSb double barrier structures while only two electron levels have been obtained in one band model. A multiband model of the semiconductor materials has been developed. The model includes six bands: two conduction bands two light- and two heavy-hole valence bands. The multiband equations have been used to calculate the quasi-discrete energy levels and wave functions for electrons in the quantum well of the Resonant Tunneling Diodes with AlGaSb/InAs/AlGaSb double barrier structures . The current-voltage characteristics has been calculated in the frame of the sequential tunneling model. The current-voltage characteristics are very sensitive to the width of the spacer. An electron transport within the conduction band is highly dependent on the coupling between the conduction and valence bands and an accurate estimate of current density requires the application of a multi-band model. A six-band Kane model yields very good agreement with experimental measurement.