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Title: Negative magnetoresistance in indium antimonide
Author: Ellis, Terry
ISNI:       0000 0001 3446 6173
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1976
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Negative longitudinal miagnetoresistance in indium antimonide subject to a quantizing magnetic field [h oc > kT and oc tau >> 1 where oc is the cyclotron frequency] has been investigated under ohmic and non-ohmic conditions. Conduction band electron concentrations ranged from 1 x 1014 cm up to 2.23 x 10 15 cm-3. Under ohmic conditions the negative magnetoresistance was studied at various stabilized temperatures between 4.2°K and 130°K. Non-ohmic results were taken at 4.2°K, using pulsed electric fields up to 10 V cm-1 (5A) to inducefree carrier heating. Using an "electron temperature model" to represent the energy distribution of the electron system, the ohmic and non-ohmic behaviour are compared. The comparison yields soma idea of the validity of this model in the presence of large magnetic and electric fields. The mechanism proposed for the observed negative magneto-resistance is the magnetic field reduction of the small-angla scattering from collisions with the ionized impurities, as originally proposed theoretically by Argyres and Adams (1956) and extended by Dubin skaya (1969). A computer programme is formulated for the extreme quantum limit [h o c > kT and EF] where only the ground state Landau level is occupied. As well as incorporating arbitrary degeneracy the calculations include the effect of drift momentum relaxation by small angle forward scattering events. These contribute to momentum relaxation because of the energy uncertainty of an. electron associated with finite collision times. The role of higher Landau energy levels is also considered. The inclusion of the forward scattering events results in a fairly good quantitative agreement with experiment. Various theoretical approximations and the effects of sample inhomogeneity are discussed as limitations on the agreement. An experimental and theoretical review of the phenomenon of negative magnetoresistance in semiconductors, associated with a variety of mechanisms, is also given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physics