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HL: Fachverband Halbleiterphysik

HL 90: Poster III

HL 90.15: Poster

Donnerstag, 10. März 2016, 16:00–19:00, Poster A

Electronic structure of lead halide perovskite — •Daniel Niesner^1,2, Tyler J. S. Evans¹, Bryan J. Kudisch¹, Prakriti P. Joshi¹, Kiyoshi Miyata¹, Xiaoxi Wu¹, M. Tuan Trinh¹, Haiming Zhu¹, Manuel Marks¹, and X.-Y. Zhu¹ — ¹Department of Chemistry, Columbia University, New York, NY 10027, USA — ²Festkörperphysik, FAU Erlangen-Nürnberg, D-91058 Erlangen, Germany

Angle-resolved photoelectron spectroscopy (ARPES) and two-photon photoelectron spectroscopy give insight into the valence and conduction band electronic structure of semiconductors. Doping levels can directly be extracted. Experiments require samples with well-defined surfaces. We report the preparation of high-quality polycrystalline thin films of (CH₃NH₃)PbI₃ on native silicon oxide on Si(111), sapphire, and PbSe(001). The (110) crystalline axis is orientated along the surface normal. Surface roughness is 1 nm. ARPES data are in semiquantitative agreement with band structure calculations. The valence band is located 1.5± 0.1 eV below the Fermi level E_F. The films on oxide surfaces are highly to degenerately n-doped, with the conduction band minimum up to 0.08 eV below E_F. Photoemission techniques are combined with optical spectroscopy taking into account the Burstein shift resulting from the high doping level. The band gap is 1.535± 0.030 eV, in good agreement with the reported value for single-crystalline (CH₃NH₃)PbI₃.