| A reliable knowledge of the transport properties of semiconductor materials is essential for the development and understanding of a number of electronic devices. In this thesis, the work on developing a Hall Effect measurement system with software based data acqui- sition and control for a temperature range of 300K-700K will be described. A system was developed for high temperature measurements of materials including single crystal diamond, poly-crystalline diamond, and thermoelectric compounds. An added capability for monitor- ing the current versus voltage behavior of the contacts was used for studying the influence of ohmic and non-ohmic contacts on Hall Effect measurements. The system has been primar- ily used for testing the transport properties of boron-doped single crystal diamond (SCD) deposited in a microwave plasma-assisted chemical vapor deposition (MPCVD) reactor [1]. Diamond has several outstanding properties that are of high interest for its development as an electronic material. These include a relatively wide band gap of 5.5 (eV), high thermal conductivity, high mobility, high saturation velocity, and a high breakdown voltage. For a temperature range of 300K-700K, IV curves, Hall mobilities and carrier concentrations are shown. Temperature dependent Hall effect measurements have shown carrier concentrations from below 1017cm --3 to approximately 1021 cm--3 with mobilities ranging from 763( cm2/V s) to 0.15(cm 2/V s) respectively. Simulation results have shown the effects of single and mixed carrier models, activation energies, effective mass and doping concentrations. These studies have been helpful in the development of single crystal diamond for diode applications. Reference materials of Ge and GaAs were used to test the Hall Effect system. The system was also used to characterize polycrystalline diamond deposited on glass for electrochemical applications, and Mg2(Si,Sn) compounds which are promising candidates of low-cost, light weight and non-toxic thermoelectric materials made from abundant elements and are suited for power generation application in the intermediate temperature range of (600 K - 800 K). In this work the thermoelectric materials were synthesized by a solid-state reac- tion using a molten-salt sealing method. The ingots produced were then powder processed, followed by pulsed electric sintering (PECS) densification. A set of Mg2.08Si0.4--x Sn0.6Sbx (0 ≤ x ≤ 0.072) compounds were investigated and a peak ZT of 1.50 was obtained at 716 K in Mg2.08Si 0.364Sn0.6Sb0.036 [2]. The high ZT value is related to a high electrical conductivity in these samples, which are possibly caused by a magnesium deficiency in the final prod- uct. Analysis of the measured results using LabVIEW and MATLAB developed programs showed good agreement with expected results and gave insight on mixed carrier dopant concentrations.;[1] I. Berkun, S. N. Demlow, N. Suwanmonkha, T. P. Hogan, and T. A. Grotjohn, "Hall Effect Measurement System for Characterization of Doped Single Crystal Diamond," in MRS Proceedings, vol. 1511, Cambridge Univ Press, 2013.;[2] P. Gao, I. Berkun, R. D. Schmidt, M. F. Luzenski, X. Lu, P. B. Sarac, E. D. Case, and T. P. Hogan, "Transport and Mechanical Properties of High-ZT Mg2. 08si0. 4- x Sn0. 6sb x Thermoelectric Materials," Journal of Electronic Materials, pp. 1--14, 2013. |
