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Fabrication of Sb-doped CIGS by selenization of stacked elemental layer and thin solar cellJian, Chong-Yao 27 August 2012 (has links)
This study is using selenization of stacked elemental layers to form Cu(In,Ga)Se2(CIGS). In the process, use Cu/Sb/In/Ga/Se precursor to heat to 550 oC at Se vapor in vacuum chamber. From the result of XRD¡BRaman and EPMA, that show of the precursor do not form to CIGS. After that, The result of using different layers precursor to form CIGS show that only Cu/In/GaSe/Se reach to form CIGS, but it still has second phase. According to the literature¡Athe reason for the formation of CIGS selenide process due to interdiffusion caused the formation of ternary solid phase, the solid phase diffusion reaction could be hampered.And then change to use rapid thermal selenization to form CIGS with two step of heating (hold at 300 oC and 650 oC) at N2 atmosphere. The laminated follow the best results in the selenide process Cu/In/GaSe/Se precursors in Se atmosphere, the (112) preferred orientation is 26.8o-26.9o in the XRD results of the fixed process conditions. EPMA composition analysis and comparison of Ga actual amount will increase with the estimated value of the amount of increase(Estimated value 4atom% actual value 2atom%¡FEstimated value 9.2tom% actual value 10atom%¡AGa/¢»=0.32), but the composition has yet to amend. Then will join Sb on CIGS observed from the SEM results Sb does improve the CIGS thin film flatness as well as to help grain growth in rapid thermal selenization, grain size of about 1 to 3£gm.
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The importance of elemental stacking order and layer thickness in controlling the formation kinetics of copper indium diselenideThompson, John O., 1962- 12 1900 (has links)
xiii, 84 p. ; ill. / This dissertation describes the deposition and characterization of an amorphous thin film with a composition near that of CuInSe 2 (CIS). The creation of an amorphous intermediate leads to a crystalline film at low annealing temperatures. Thin films were deposited from elemental sources in a custom built high vacuum chamber.
Copper-selenium and indium-selenium binary layered samples were investigated to identify interfacial reactions that would form undesired binary intermediate compounds resulting in the need for high temperature annealing. Although the indium-selenium system did not form interfacial compounds on deposit, indium crystallized when the indium layer thickness exceeded 15 angstroms, disrupting the continuity of the elemental layers. Copper-selenium elemental layers with a repeat thickness of over 30 angstroms or compositions with less than 63% selenium formed CuSe on deposit.
Several deposition schemes were investigated to identify the proper deposition pattern and thicknesses to form the CIS amorphous film. Simple co-deposition resulted in the nucleation of CIS. A simple stacking of the three elements in the older Se-In-Cu at a repeat thickness of 60 angstroms resulted in the nucleation of CuSe and sometimes CIS. The CIS most likely formed due to the disruption of the elemental layers by the growth of the CuSe. Reduction of the repeat thickness to 20 angstroms eliminated the nucleation of CuSe, as predicted by the study of the binary Cu-Se layered samples, but resulted in the nucleation of CIS, similar to the co-deposited samples.
To eliminate both the thick Cu-Se region, and prevent the intermixing of all three elements, a more complex deposition pattern was initiated. The copper and selenium repeat thicknesses were reduced into a Se-Cu-Se-Cu-Se pattern followed by deposition of the indium layer at a total repeat thickness of 60 angstroms. At a Se:Cu ratio of 2:1 and the small repeat thickness, no Cu-Se phases nucleated. Additionally, the Cu-In interface was eliminated. For this deposition scheme, films with a selenium rich composition relative to CuInSez were generally amorphous. Those that were Cu-In rich always nucleated CIS on deposit. Annealing of all samples produced crystalline CIS. / Adviser: David C. Johnson
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