Topological band structure in InAs/GaSb/InAs triple quantum wells

We present gate voltage and temperature dependent transport measurements of topological insulators based on InAs/GaSb/InAs triple quantum wells (TQW). Gate voltage dependent measurements enable us to monitor two electrons densities deep in the nonhybridized electron regime related to both InAs-wells. Furthermore, they reveal a clear hybridization gap and a Van Hove singularity (VHS) in the valence band (VB) because of the hybridized electron-hole band structure. Electron and hole densities coexist if the Fermi energy (EF) is within the gap and the bottom of the valence band at the Γ point whereas only single carrier types can be found far in the conduction or valence band. Thus, we are able to identify the topological band structure of this material system. Additionally, we study the temperature evolution of the hybridization gap and find a rather temperature insensitive hybridization gap energy.