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The transport and optical band gaps for the organic semiconductor tin (II) phthalocyanine (SnPc) and the complete energy band profiles have been determined for organic-inorganic interfaces between SnPc and III-V semiconductors. High throughput measurement of interface energetics over timescales comparable to the growth rates was enabled using in situ and real-time photoelectron spectroscopy combined with Organic Molecular Beam Deposition. Energy band alignment at SnPc interfaces with GaAs, GaP, and InP yields interface dipoles varying from -0.08 (GaP) to -0.83 eV (GaAs). Optical and transport gaps for SnPc and CuPc were determined from photoelectron spectroscopy and from optical absorption using spectroscopic ellipsometry to complete the energy band profiles. For SnPc, the difference in energy between the optical and transport gaps indicates an exciton binding energy of (0.6 ± 0.3) eV. [ABSTRACT FROM AUTHOR]

The interaction between tin phthalocyanine (SnPc) and polycrystalline iron has been studied with XPS and synchrotron radiation excited XPS. After incremental annealing of a thin film of SnPc on a polycrystalline iron substrate, a low binding energy component of the Sn 3d core level became increasingly abundant. This component is attributed to metallic tin, and thus, it is suggested that a substitution reaction has occurred. Quantitative analysis of the carbon and nitrogen core level intensities is consistent with such a substitution. The reaction is observable at room temperature, but is enhanced at elevated temperatures.It is also shown that after thermal desorbtion of the SnPc adlayer, the residual carbon component is significantly reduced relative to a thermally cleaned polycrystalline surface. [Copyright &y& Elsevier]

Abstract: For monolayer films of metal phthalocyanines deposited on the two-domain Ge (001) 2×1 surface, NEXAFS measurements indicate that the molecules are tilted at an angle of 24–26° to the substrate. This result is further investigated here using NEXAFS and STM. First, the NEXAFS experiments previously carried out on the two-domain surface were repeated on a single domain Ge (001) 2×1 surface: it was found that NEXAFS perpendicular and parallel to the dimer rows were almost identical. Second, STM measurements indicate that most molecules adopt a unique bonding site, relative to the dimer rows and with the plane of the molecule parallel to the surface; however, some other bonding locations are also observed. Together these experiments suggest that a uniform molecular tilt is not an appropriate description; other possible explanations are briefly considered. [Copyright &y& Elsevier]

An organic-III-V hybrid semiconductor interface has been studied using real-time photoelectron spectroscopy and x-ray absorption spectroscopy to reveal the evolving morphology and molecular structure within the organic layer during thin film growth. This new approach to in situ characterization has been enabled by electron detection using a direct electron-counting array detector coupled to a hemispherical electron analyzer. The nonplanar tin phthalocyanine (SnPc) molecules initially form a uniform layer within which they have a distinct molecular orientation relative to the S-passivated gallium arsenide substrate surface [GaAs:S(001)]. The critical thickness of 0.9 nm that marks the transition between layered and clustered growth, determined from the photoemission measurements, corresponds to a single molecular layer with the molecules oriented at an angle of (39±2)° to the substrate plane. This value is confirmed by angle-resolved near-edge x-ray absorption fine structure measurements in the same experimental environment. However, the angle is less for the thicker films as the molecule-molecule interaction dominates over the molecule-substrate interaction and the structure is close to that of the bulk triclinic SnPc crystal. [ABSTRACT FROM AUTHOR]