A study of rapid thermal selenization process of CuInSe2 films

• Main Authors: Chia-jui Pan, 潘家叡
• Other Authors: Bae-Heng Tseng
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/05022824861735496439

碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 97 === By evaporating single element to grow two kinds of stacked layer precursors In/Cu/Se and In/Se/Cu first, In/Cu/Se precursor forms as CuSe2, CuSe and In metal phase, but In/Se/Cu precursor forms mainly as Cu11In9 alloy, In metal phase and amorphous Se. In RTA selenization process, the two kinds of stacked layer precursors form to CuInSe2 (for short as CIS) thin film in different reaction mechanisms, but both of the two stacked layers form to CIS with rough surface and uncompact structure, not the ideal thin film. Replacing by co-evaporating two elements to grow two kinds of binary stacked layrer precursors InSe/CuSe/Se and InSe/Cu/InSe/Se, finds that, after the RTA selenization process, both of the two precursors form CIS with good smoothness and compactness, and InSe/CuSe/Se precursor with much better structure than the other, having mean grain size in about 1~3μm. In this result, appears that if skipping the stage which single element reacts with Se, generating the selenide InxSey, CuxSey (Such as InSe, In2Se3, CuSe, Cu2Se et cetera.), and using In-Se, Cu-Se binary stacked precursors in RTA process directly can acquire better CIS structure. And then, growing InSe/CuSe/Se stacked layer on Mo metal back contact, finds the phenomenon that the formed CIS thin film has many circle bulges structure on Mo thin film. After investigating this case, the reason was considered as the remaining compressive stress of Mo thin film (-272.9MPa). The interface problem of Mo/CIS has been solved by tuning the remaining stress of Mo with 1μm thickness to compressive stress -194MPa, and 1μm thickness CIS thin film is grown on that. However, if the remaining stress continuingly drecrese to almost no stress 1MPa or tensile stress 709.9MPa, CIS thin film peels with Mo thin film from the substrate. In the end, analyzing the CIS thin film formed by InSe/CuSe/Se stacked layer precursor (Cu/In ratio is 24%/26%), the result shows that the CIS film is a P-type In-rich thin film, the sheet resistence is 6.8*106Ω/ □, carrier mobility is 1.103*102 cm2/V-s, carrier density is 1.318*1018 cm-3, and energy gap is about 1.0eV, the absorption coefficient is above 6.5*104cm-1, and the composition all over the film is very close to each other，appearing this film with nice composition homogenization.