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

Abstract

We present gate voltage and temperature dependent transport measurements of InAs/GaSb/InAs triple quantum wells (TQWs) with a designed hybridization gap energy of 4 meV comparable to its traditional double quantum well counterpart. Gate voltage dependent measurements enable us to monitor two electron densities deep in the nonhybridized electron regime and further reveal a clear hybridization gap and a Van Hove singularity in the valence band as a result of the hybridized electron-hole band structure of the TQWs. The evolution of the charge carrier densities and types is studied in detail. Electron and hole densities coexist if the Fermi energy is within the gap and the bottom of the valence band at the \ensuremath{\Gamma} point. On the contrary, only single carrier types can be found far in the conduction and valence band. Thus, we are able to identify the topological band structure of these TQWs. Furthermore, the temperature evolution of the hybridized gap of the triple quantum well is studied. We find a rather temperature insensitive hybridization gap energy.