ELECTRON-SCATTERING BY OPTICAL PHONONS IN ALXGA1-XAS GAAS/ALXGA1-XAS QUANTUM-WELLS/

The scattering of a quasi two-dimensional electron gas by optical phon ons in selectively doped AlxGa1-xAs/GaAs/AlxGa1-xAs quantum wells is s ystematically studied in order to determine the effect of phonon confi nement. The electron states are calculated solving self-consistently S chrodinger and Poisson equations to obtain an accurate dependence upon the structure parameters and the temperature. We study the way the sc attering is affected by the form of the phonons calculating the mobili ty using three models for the phonons. They are considered: (a) as thr ee dimensional (3D), (b) as a set of confined and interface phonons, a nd (c) as the normal modes of the heterostructure. The relaxation time s for the electron energy subbands are calculated solving the system o f Boltzmann equations. The effect of the temperature and the well widt h variation is also investigated. The results are in a good agreement with experimental measurements. The agreement is only slightly depende nt on the model used for the phonons and becomes best when the effect of the heterostructure on the phonon modes is taken into account.