22 September 2010 Room temperature transport measurements on Bridgman-grown CuInSe2 with added sodium
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Proceedings Volume 7750, Photonics North 2010; 775030 (2010) https://doi.org/10.1117/12.869576
Event: Photonics North 2010, 2010, Niagara Falls, Canada
Abstract
Thermoelectric power, Hall coefficient and resistivity measurements were carried out on material cut from monocrystalline ingots of CuInSe2. The ingots were grown using a vertical-Bridgman procedure, whereby Cu, In and Se were melted and directionally cooled within a sealed quartz ampoule. When stoichiometric proportions of the starting elements were used, the material was always p-type, with hole concentrations of the order of 1017-1018 cm-3. However, the incorporation of a sufficient amount of sodium (0.3 at. %) into the melt was seen to result in n-type material, with electron concentrations of the order of 1016. This conversion from p to n was hindered by the inclusion Se above stoichiometry into the ampoule, and more Na was required for the material to change type. The mobility of the p-type samples, with low sodium additions (0-0.2 at. %), was on average 17 cm2V-1s-1, and was seen to be higher for material grown from melts containing excess Se, corresponding to the chemical formula CuInSe2.2, than from stoichiometry. SEM/EDX (Scanning electron microscope / Energy-dispersive X-ray spectroscopy) analysis of the ingots after growth indicated no sodium residing within the interior of the bulk material, but a significant amount was found on the exterior surface in the case of an ingot grown with CuInSe2.05 and 5 at. % Na. Various deposits found within the ampoules after growth were analyzed, including a copper-rich precipitate found only in ampoules which included a high concentration of Na and a low concentration of excess Se, resulting in n-type material.
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H. F Myers, C. H. Champness, I. Shih, "Room temperature transport measurements on Bridgman-grown CuInSe2 with added sodium", Proc. SPIE 7750, Photonics North 2010, 775030 (22 September 2010); doi: 10.1117/12.869576; https://doi.org/10.1117/12.869576
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