Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 98: Focus Session: Functionalization of Semiconductors III

HL 98.5: Vortrag

Freitag, 11. März 2016, 11:30–11:45, H16

Atomic-scale investigation of photovoltaic GaN/Si(111) hetero-interfaces using photoexcited scanning tunneling microscopy and spectroscopy — •Fei-Man Hsiao¹, Yen-Chin Huang², Bo-Chao Huang³, Philipp Ebert⁴, and Ya-Ping Chiu⁵ — ¹Dept. of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan — ²Dept. of Physics, National Cheng Kung University, Tainan 70101, Taiwan — ³Institute of Physics, Academia Sinica, Taipei 11529, Taiwan — ⁴Peter Grünberg Institut, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — ⁵Dept. of Physics, National Taiwan Normal University, Taipei 11677, Taiwan

Direct observation of the light response across high-efficiency GaN/Si(111) solar cell heterojunctions was spatially resolved at atomic scale by cross-sectional scanning tunneling microscopy and spectroscopy. By employing a laser with a wavelength of 405 nm at the interface, electron/hole pairs are expected to be primarily generated at the Si side. However, the analysis reveals changes of the tunnel currents at both sides of the hetero-interface under illumination, indicating the transport of excited carriers through the interface. This observation was verified by band alignment calculations: While excited electrons can pass the interface due to the flat alignment of the conduction bands, excited holes do not have sufficient energy to overcome the valence band discontinuity.