Ultrafast electron dynamics in ZnO/Si micro-cones

• Published in: Applied physics. A, Materials science & processing Vol. 98; no. 4; pp. 701 - 705
• Main Authors: Magoulakis, E., Papadopoulou, E. L., Stratakis, E., Fotakis, C., Loukakos, P. A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.03.2010; Springer
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Defects; Exact sciences and technology; Excitation; Iii-v semiconductors; Lasers; Machines; Manufacturing; Materials science; Nanotechnology; Nonlinear dynamics; Optical and Electronic Materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Physics and Astronomy; Processes; Rapid Communication; Silicon substrates; Surfaces and Interfaces; Thin Films; Trapping; Zinc oxide; Pump Pulse Duration; Probe Photon; Pump Beam; Conical Struc; Ultrafast Dynamic; Thin films; Charge carrier trapping; Energy gap; Reflection spectrum; Surface morphology; Roughness; Zinc oxide; Renormalization; Electron-defect interactions; Time resolved spectra; Ultrafast process
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-010-5558-7

A comparative study of the ultrafast dynamics on ZnO thin films deposited on flat Si substrates and on Si micro-cones following ultrashort laser excitation has been carried out using time-resolved optical spectroscopy. By monitoring the transient band gap renormalization induced by nonlinearly excited carriers it is found that fast electron scattering and trapping occurs more efficiently in the micro-cones as compared to the flat films. This enhanced trapping efficiency is attributed to the defects and imperfections that are introduced by the increased surface roughness due to the conical shape.