Accession Number : ADA334656

Title :   Alloy Dependence of Electron-Phonon Interactions in Double Barrier Structures

Descriptive Note : Final rept

Corporate Author : AIR FORCE RESEARCH LAB BOLLING AFB DC

Personal Author(s) : Wallis, Corinne R.

PDF Url : ADA334656

Report Date : 12 JAN 1996

Pagination or Media Count : 221

Abstract : We have carried out a systematic experimental study of electron-phonon interactions in a series of GaAs/Al(x)Ga(1-x)As double barrier structures as a function of the alloy concentration in the barrier. We have measured current-voltage and conductance-voltage curves associated with phonon-assisted tunneling with magnetic fields from 0 to 6.8 Tesla. Fan diagrams are constructed and used to measure the energies of the contributing phonons and to compare the levels of different modes to the current. It is found that phonons with at least three different energies contribute to the phonon-assisted tunneling current in samples with x > or = 0.5 and with at least two different energies with x < or = 0.4. We also present results of a fitting routine to experimentally determine the relative strengths of contributions to the phonon-assisted tunneling current at 0 Tesla. These measurements indicate that as the aluminum concentration in the barriers decrease, the contribution decreases from modes with energies of bulk AlAs LO phonons, while the contribution increases from modes with energies of bulk GaAs TO phonons. Observations are in good qualitative agreement with theoretical calculations which incorporate the modified dielectric continuum model to estimate the phonon potentials. We review how the phonon-assisted tunneling current may be calculated for a GaAs/AlAs double barrier structure using the dielectric continuum model to compute the localized phonon potentials.

Descriptors :   *ALLOYS, *PHONONS, OPTICAL PROPERTIES, MAGNETIC FIELDS, COMPUTATIONS, MODELS, INTERACTIONS, GALLIUM ARSENIDES, TUNNELING(ELECTRONICS), STRUCTURES, DIELECTRICS, THESES, ELECTRONS, RESONANCE, BARRIERS, ALUMINUM ARSENIDES, CIRCUITS, SOLID STATE ELECTRONICS, FITTING FUNCTIONS(MATHEMATICS).

Subject Categories : Electrical and Electronic Equipment
      Electrooptical and Optoelectronic Devices
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE