Piezomodulated reflectivity of asymmetric and symmetric ${\mathrm{Al}}_{\mathit{x}1}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}1}$As/GaAs/${\mathrm{Al}}_{\mathit{x}3}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}3}$As single quantum wells

The piezomodulated reflectivity spectra of compositionally asymmetric ${\mathrm{Al}}_{\mathit{x}1}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}1}$As/GaAs/${\mathit{Al}}_{\mathit{x}3}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}3}$As single quantum wells exhibit transitions from bound to quasibound and quasibound to quasibound states. The quasibound states, which exist in the continuum between the lower and upper barrier energies, participate resonantly in interband transitions. The piezomodulated reflectivity spectrum of an asymmetric quantum well designed with the appropriate parameters shows the absence of a bound state. Symmetric quantum wells are compared with their asymmetric counterparts of equal well width. When 1s and 2s excitonic signatures are observed, their separation is used to determine excitonic corrections.