Interface and surface optical phonons in a free-standing cylindrical quantum-well wire

✍ Scribed by Li Zhang; Hong-Jing Xie

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 412 KB
• Volume: 363
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2005.03.016

✦ Synopsis

Under dielectric continuum approximation, interface optical (IO) and surface optical (SO) phonon modes as well as the corresponding Fro¨hlich electron-phonon interaction Hamiltonian in a free-standing cylindrical quantum-well wire (QWW) were derived and studied. Numerical calculations on GaAs=Al x Ga 1Àx As cylindrical QWWs have been performed. Results reveal that, in the case of taking the ''two-mode'' behavior of the Al x Ga 1Àx As material into account, there have four branches of IO phonon modes and two branches of SO phonon mode, and the dispersion frequencies of IO or SO phonon modes sensitively depend on the Al mole fraction x in Al x Ga 1Àx As material and the wave-vector in z direction k z . With the increasing of k z and quantum number m, the frequency of each IO mode approaches one of the two frequency values of the single GaAs=Al x Ga 1Àx As heterostructure, and the electrostatic potential distribution of the phonon mode tends to be more and more localized at a certain interface or surface, meanwhile, the coupling between the electron-IO or -SO phonon becomes weaker.