Bandgap and Band Offsets Determination of Semiconductor Heterostructures using Three-terminal Ballistic Carrier Spectroscopy

TL;DR

This paper introduces a novel three-terminal ballistic carrier spectroscopy method to accurately measure semiconductor bandgaps and heterojunction band offsets without prior material parameters, demonstrating high precision on GaAs-based structures.

Contribution

The method allows self-consistent measurement of bandgaps and band offsets in heterostructures with high resolution, independent of existing material parameters.

Findings

Measured bandgaps of AlGaAs and AlGaInP with meV resolution at 4.2 K.

Determined Gamma band offset ratio of 60.4:39.6 for GaAs/AlGaAs interface.

Discovered a non-monotonic Al composition dependence of conduction band offset in GaAs/AlGaInP.

Abstract

Utilizing three-terminal tunnel emission of ballistic electrons and holes, we have developed a method to self-consistently measure the bandgap of semiconductors and band discontinuities at semiconductor heterojunctions without any prerequisite material parameter. Measurements are performed on lattice-matched GaAs/AlxGa1-xAs and GaAs/(AlxGa1-x)0.51In0.49P single-barrier heterostructures. The bandgaps of AlGaAs and AlGaInP are measured with a resolution of several meV at 4.2 K. For the GaAs/AlGaAs interface, the measured Gamma band offset ratio is 60.4:39.6 (+/-2%). For the GaAs/AlGaInP interface, this ratio varies with the Al mole fraction and is distributed more in the valence band. A non-monotonic Al composition dependence of the conduction band offset at the GaAs/AlGaInP interface is observed in the indirect-gap regime.