tailieunhanh - Báo cáo hóa học: " Ultrafast Carrier Relaxation in InN Nanowires Grown by Reactive Vapor Transport"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Ultrafast Carrier Relaxation in InN Nanowires Grown by Reactive Vapor Transport | Nanoscale Res Lett 2009 4 122-129 DOI s11671-008-9211-8 NANO EXPRESS Ultrafast Carrier Relaxation in InN Nanowires Grown by Reactive Vapor Transport Andreas Othonos Matthew Zervos Maria Pervolaraki Received 18 October 2008 Accepted 11 November 2008 Published online 26 November 2008 to the authors 2008 Abstract We have studied femtosecond carrier dynamics in InN nanowires grown by reactive vapor transport. Transient differential absorption measurements have been employed to investigate the relaxation dynamics of photogenerated carriers near and above the optical absorption edge of InN NWs where an interplay of state filling photoinduced absorption and band-gap renormalization have been observed. The interface between states filled by free carriers intrinsic to the InN NWs and empty states has been determined to be at eV using CW optical transmission measurements. Transient absorption measurements determined the absorption edge at higher energy due to the additional injected photogenerated carriers following femtosecond pulse excitation. The nondegenerate white light pump-probe measurements revealed that relaxation of the photogenerated carriers occurs on a single picosecond timescale which appears to be carrier density dependent. This fast relaxation is attributed to the capture of the photogenerated carriers by defect surface related states. Furthermore intensity dependent measurements revealed fast energy transfer from the hot photogenerated carriers to the lattice with the onset of increased temperature occurring at approximately 2 ps after pulse excitation. A. Othonos El Department of Physics Research Centre of Ultrafast Science University of Cyprus . Box 20537 1678 Nicosia Cyprus e-mail othonos@ M. Zervos M. Pervolaraki Department of Mechanical Engineering Materials Science Group University of Cyprus . Box 20537 1678 Nicosia Cyprus Keywords InN Nanowires Carrier dynamics Femtosecond differential absorption spectroscopy Absorption .