Fig. 1: Lattice-matched double Si/Ge bilayer, band structure, device architecture.
From: Electron–hole superfluidity in strained Si/Ge type II heterojunctions
a Below the critical thickness for plastic relaxation, epitaxial Ge and Si layers are lattice matched to the underlying SiGe, with compressive and tensile strain, respectively. b Band structure of low-lying bands resulting in a double quantum well structure. Due to the type II band alignment at the strained Si/Ge heterojunction, electrons (Δ2 states) are confined in tensile strained Si and holes (HH states) in compressively strained Ge. c Material stack with embedded Si/Ge bilayer and an envisaged device architecture, characterized by independent n++ and p++ contacts, and gate electrodes to tune independently the electron and hole densities in the bilayer.
