کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
195348 | 459812 | 2007 | 7 صفحه PDF | دانلود رایگان |
Electrocrystallization of Sb and the compound semiconductor ZnSb has been investigated by in situ SPM methods at the electrified ionic liquid/Au(1 1 1) interface at an elevated temperature of 50 °C for the first time employing the ionic liquid ZnCl2–[C4mim]+Cl− (45:55). Prior to the underpotential deposition (UPD) process of Sb, ZnCl3− anions adsorb on the gold surface at the open-circuit potential (OCP). An ordered region – showing the characteristic of a Moiré-like pattern – coexists with a disordered region indicative of an interfacial phase transition. When the potential is reduced to −0.40 V versus Pt/Pt(II), 2D electrocrystallization of Sb starts showing a typical 3×3 structure of the first monolayer. Further decreasing the potential to −0.5 V a second layer of Sb islands occurs. Stepping the potential from the UPD region to −0.60 V, the OPD of Sb sets in showing randomly dispersed clusters of homogeneous size. Near the ZnSb deposition potential, at ∼−0.95 V, a nearly homogeneous distribution of clusters of spherical shape with diameters up to 15 nm is found. Their corresponding STS curves exhibit an obvious semiconducting behaviour with a gap-energy of ∼0.6 ± 0.2 eV. Experiments at deposition conditions on the Sb-rich or Zn-rich side relative to the ZnSb deposition potential show an obvious doping effect – in the case of Zn excess – which is revealed by the corresponding normalized conductance (NC) spectra.
Journal: Electrochimica Acta - Volume 53, Issue 2, 1 December 2007, Pages 518–524