Impurity scattering enhancement of the acoustic phonon-limited intersubband transition rate

Summary form only given. Recently, infrared lasers based on intersubband transitions in multiple asymmetric quantum wells have been proposed and a 4.2-/spl mu/m semiconductor injection laser has been demonstrated. They rely on electronic transitions between conduction band states arising from the quantization in semiconductor heterostructures. Here, we propose the depopulation of the lower laser level to the ground state by means by acoustic phonon and impurity scattering, in intersubband three level lasers emitting below the optical phonon wavelength. Because the lasing transition is limited by the acoustic phonon rate, we aim to achieve population inversion by enhancing the acoustic phonon-limited depopulation of the lower laser level to the ground state through impurity scattering.