Bandgap and band offsets determination of semiconductor heterostructures using three-terminal ballistic carrier spectroscopy

Abstract

Utilizing ambipolar tunnel emission of ballistic electrons and holes, we have developed a model-independent method to self-consistently measure bandgaps of semiconductors and band offsets at semiconductor heterojunctions. Lattice-matched GaAs/Al_xGa_1-xAs and GaAs/(Al_xGa_1-x)_0.51In_0.49P (100) single-barrier heterostructures are studied at 4.2 K. For the GaAs/AlGaAs interface, the measured Γ band offset ratio is 60.4:39.6 ( ± 2%). For the heteroanion GaAs/AlGaInP (100) interface, this ratio varies with the Al composition and is distributed more in the valence band. The indirect-gap X band offsets observed at the GaAs/AlGaInP interface deviates from predictions by the transitivity rule.