Misfit Strain in Superlattices Controlling the Electron-Lattice Interaction via Microstrain in Active Layers

Figure 1

Pictorial view of the superlattice with a first layer with a first material characterized by lattice parameter 𝑎₁ and a second layer with a second material characterized by a lattice parameter 𝑎₂. The superlattice misfit strain is 𝜂=(𝑎₁−𝑎₂)/𝑎 where a is the mean averaged lattice parameter 𝑎=(𝑎₁+𝑎₂)/2. The compensated superlattice, showed on the right, has an overall microstrain zero, with 𝑎 first layer under compressive microstrain 𝜀(𝑎−𝑎₁)/𝑎 and a second intercalated layer under a tensile microstrain (𝑎₂−𝑎)/𝑎. It is therefore easy to show, because of the balance in the compensated superlattice of the microstrain, that the misfit strain is related to microstrain by the following relationship 𝜂=2𝜀.