RP-Department of Physics

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Design and fabrication of a simple four point probe system for electrical characterization of thin films
(2011-07) Agumba, J.O.; Karimi, P.M.; Okumu, J.; Njoroge, W.K.
The electrical characteristics of semiconductor thin films are of great practical interest in microelectronics industry hence the need to measure these parameters in a cheaper and faster manner possible. In this study, we report on design and fabrication of a cheap, simple and portable computer-aided four point probe system for thin film sheet resistivity measurement. The designed system has been used to measure sheet resistivity of Cu2O semiconductor thin films prepared at different sputter conditions by DC reactive magnetron sputtering technique. With the Van der Pauw set-up and a square symmetry adopted, sheet resistivity of Cu2O thin films at room temperature of 23oC was found to be 55.65 Ω cm when measured using the system. However, as the samples were exposed to temperature rise, the sheet resistivity was found to decrease and was at its minimum value of 29.67 Ω cm at 170oC. The sheet resistivity of Cu2O thin films were further found to increase with increase in sputter pressure during film preparation. Films deposited at sputtering pressure of 1.8x10-2 mbar had sheet resistivity of 33.64 Ω cm and this increased to 62.23 Ω cm for films deposited at higher sputtering pressure of 2.4x10-2 mbar.