Piezomodulation spectroscopy: A powerful investigation tool of heterostructures

We discuss the potential of piezomodulated spectroscopy to identify electron and/or hole states, together with their spatial localizations, in strained epilayers, quantum wells, and superlattices. The potential of the technique is illustrated using several experimental results concerning GaAs/${\mathrm{Ga}}_{\mathit{x}}$${\mathrm{Al}}_{1\mathrm{-}\mathit{x}}$As, CdTe/ZnTe, and CdTe/${\mathrm{Cd}}_{\mathit{x}}$${\mathrm{Zn}}_{1\mathrm{-}\mathit{x}}$Te heterostructures.