Electron scattering and capture rates in quantum wells by emission of hybrid optical phonons - art. no. 205304

Intra- and intersubband scattering and electron capture rates are considere d when mediated by hybrid optical phonons in an AlAs/GaAs/AlAs double heter ostructure confined between two outer metallic barriers. In evaluating scat tering rates we concentrate first on an infinite quantum well for the elect rons and show that the presence of the outer metal barriers results in redu ctions of the intra- and intersubband scattering rates due to the suppressi on of the interfacelike modes. For a quantum well with a finite depth we fi nd that the outer barriers are responsible for the existence of a discrete energy spectrum above the well. The electron capture process under these ci rcumstances is defined as the electron transition from the first electron s ubband above the well to all possible subbands inside the well by the emiss ion of hybrid phonons. Explicit calculations reveal that the capture rates are characterized by sharp peaks, referred to as electron resonances, which arise when a new electron state is generated on increasing the quantum wel l width. Other sharp peaks are identified as phonon resonances and arise wh en the energy of the initial state differs by a phonon energy from an elect ron state at the bottom of a quantum well subband.