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|Title:||Measurements of the Microwave Conductivity of N-Type Germanium|
|Authors:||Rahman, Mohammad Hasibur|
|Advisor:||Gunn, M. W.|
Campbell, C. K.
|Keywords:||microwave, measurements, conductivity, n-type, germanium, semiconducting, field vector|
|Abstract:||<p> An investigation has been made of the microwave reflections from the surface of a semiconducting medium with complex permittivity (^ε = εrεo -jσ/ω) at the open end of an empty rectangular waveguide. The approximate and exact solutions of the reflection coefficients at the surfaces of both finite and semi-infinite media have been found as a function of the complex permittivity of the medium. The computations of the reflection coefficients are made at the 10 and 35 GHz ranges. Measurements, which confirm these calculations, have been performed with n-type germanium, selectron, and air at the open end of a rectangular waveguide using a reflection type microwave bridge. The investigation has shown that it is possible to devise a convenient method of measuring the conductivity and dielectric constant of semiconductors.</p> <p> The theory of operation of the microwave reflection bridge together with the setting-up (matching) procedure of a practical form of the bridge has been presented. A method is also described for the correction of the measurement error which arises from the scattering coefficients at the input ports of the precision attenuator.</p> <p> A theoretical and experimental study has also been made of the small- signal microwave conductivity of n-type germanium at room temperature in the presence of a high electric field, directed at an angle θ to the microwave field. The study has shown that at frequencies such as 10 GHz, the microwave conductivity becomes anisotropic with respect to the direction of the d.c. field vector. Measurements are made on an 11.4 ohm cm, n-type germanium sample at 9.381 GHz with applied electric fields up to 1.8 KV/cm for θ = 0°, 40°, and 90°. The ''open-end-waveguide measuring technique", which allows the angle between the microwave and d.c. field vectors to be varied, was employed to measure the microwave conductivity. The results of measurements which agree with predictions, confirm the feasibility of operation of a new microwave device based on the anisotropic effect.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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