UBC Theses and Dissertations
Electron paramagnetic resonance of heavily-doped n-type silicon Quirt, John David
Spin susceptibility, g-value, and EPR linewidth data are presented for phosphorus-doped silicon samples having impurity concentrations 10¹⁸ donors/cm³ < N[sub D] 10²⁰ donors/cm³. These results are compared with the predictions of alternative simple models of the semiconductor-to-metal transition in heavily-doped semiconductor materials. At low concentrations (N[sub D] < 3 x 10¹⁸ donors /cm³) our samples behave as semiconductors in transport experiments, and are characterized by Curie-Weiss Law spin susceptibilities. Near the upper limit of our sample impurity concentration range (N[sub D] ~ 10²⁰ donors/cm³) transport properties indicate "metallic" properties and the spin susceptibility data may be represented by the Pauli expression with an effective mass slightly smaller than that usually associated with the silicon conduction band. A good representation of the experimental spin susceptibilities can be achieved with an expression which is the sum of two terms, one of which is of the Curie-Weiss form, and the other of the Pauli type. Previously published Hall coefficient data is analysed to establish the relationship between these susceptibility components and non-conducting (or partially localized) and conducting extrinsic electrons respectively. The inferred presence of partially-localized electrons even in samples with N[sub D] > 10¹⁹ donors/cm³ is discussed with respect to previously published magnetoresistance and Knight Shift data. For high impurity concentrations (N[sub D] > 10¹⁹ donors/cm³) additional analysis of the experimental data with respect to theoretical models appropriate for electrons in silicon conduction band states is presented.
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