Photogenerated carriers at defect states in polycrystalline GaN using sub-bandgap laser-excited scanning tunneling spectroscopy
ORAL
Abstract
Photo-induced carriers at defect states in GaN layers dominates the performances of nitride-based compound devices. In this work, sub-bandgap laser-excited cross-sectional scanning tunneling microscopy and spectroscopy demonstrate a great potential to obtain photo-induced electronic properties at defect-rich GaN films under the illumination condition. A spectacular enhancement in the tunneling current at positive voltages is observed in the defect-rich GaN layers under illumination, resulting from the excitation of free charge carriers at defect states. Thus, sub-bandgap laser-excited scanning tunneling spectroscopy provides us an opportunity to characterize the existence of charge carriers at defect states and demonstrates the behavior of photo-induced carriers in GaN layers.
*The authors thank the Ministry of Science and Technology (MOST), Taiwan (Project Nos. 104-2112-M-002-025-MY3,
103-2112-M-002-028-MY3, and 104-2911-I-003-514), the Helmholtz-Gemeinschaft Deutscher Forschungszentren (Impuls-
und Vernetzungsfond, Grant No. HIRG-0014), and the Deutsche Forschungsgeme
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Presenters
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Ya-Ping Chiu
- Department of Physics, National Taiwan University