Electronic Transport in InAs/GaSb Nanostructured Type-II Superlattices for Infrared Sensing and Imaging Applications

Bandgap-engineered superlattices are becoming increasingly important as a nanostructured semiconductor material platform for infrared (IR) sensing and imaging. As is the case for semiconductor-based micro/nano-scaled optoelectronic materials, accurate knowledge of the electronic transport parameters such as carrier mobility, concentration and lifetime is necessary for material optimization, device design and performance prediction. However, nanostructure superlattice-based materials and devices pose unique electronic transport characterization challenges. In addition to multiple carrier conduction from the nano-layered superlattice structure, the relevant electronic transport properties can be obscured by parasitic conduction through conductive substrates, buffer layers and/or surface inversion/accumulation layers. Yet the most formidable challenge stems from their electronic transport anisotropy: the in-plane (or parallel) conductivity can be many orders of magnitude higher than in the direction perpendicular (or vertical) to the superlattice plane. In this work, we present results of a mobility spectrum analysis-based study of electronic transport in InAs/GaSb superlattices, including extraction of electron carrier density, mobility, and steady-state electron lifetime in the lateral and vertical transport directions.