Stoichiometry and surface reconstruction of epitaxial CuInSe₂(112) films

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• 作者：A. Hofmann ; C. Pettenkofer ; ^{pettenkofer@helmholtz-berlin.de}
• 关键词：Semiconductor surface ; Chalcopyrite ; Thin film ; Solar cell
• 刊名：Surface Science
• 出版年：2012
• 出版时间：August, 2012
• 年：2012
• 卷：606
• 期：15-16
• 页码：1180-1186
• 全文大小：876 K

文摘

CuInSe₂(112) films were grown on GaAs(111)A substrates by molecular beam epitaxy. The resulting surface stoichiometry was deduced by consideration of results from various surface analytic techniques. The obtainable Cu/In stoichiometry range in XPS was 0.4-1.2, where 1.2 marks the onset of Cu_2 ?#xA0;xSe phase segregation at the surface and 0.4 corresponds to the copper-depleted surface with ordered defect compound (ODC) composition. For the stoichiometric CuInSe₂(112) surface, a c(4 ¡Á 2) reconstruction of the zinc blende surface periodicity is observed in the LEED pattern, with three rotational domains present on the flat GaAs(111) substrate. With the use of stepped (111) substrates, domain formation could be suppressed. By comparison of the LEED data and concentration depth profiles from angle-resolved XPS, two types of surface reconstructions could be distinguished. According to surface energy calculations in the literature, these correspond to surfaces stabilized by either Cu_In or 2V_Cu defects. The surface of copper-poor CuIn₃Se₅ shows no reconstruction of the zinc blende order.