1. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Optical Properties of Porous Silicon Thue-Morse Multilayers I. Rea, L. Rotiroti, I. Rendina, L. De Stefano Institute for Microelectronic and Microsystem – Dept. of Naples, National Council of Research, Naples, Italy L. Moretti DIMET – University “Mediterranea” of Reggio Calabria, Reggio Calabria, Italy

2. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Aperiodic vs Periodic  High geometric complexity  Multiple photonic band gaps  Highly localized states  Geometrical periodicity  Single photonic band gap  Bloch-like states Photonic Bandgap CrystalsPhotonicQuasi-Crystals 1)X. Jiang, Y. Zhang, S. Feng, K. C. Huang, Y. Yi, and J. D. Joannopoulos, “Photonic band gaps and localization in the Thue–Morse structures”, Applied Physics Letters 86, 201110 (2005). 2)F. Qui, R. W. Peng, X. Q. Huang, X. F. Hu, Mu Wang, A. Hu, S. S. Jiang and D. Feng, “Omnidirectional reflection of electromagnetic waves on Thue-Morse dielectric multilayers”, Europhysics Letters 68, 658-663 (2004).

3. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 The Thue-Morse sequences n th lattice  (n+1) st lattice A  ABB  BA S 0 =[A], S 1 =[AB], S 2 =[ABBA], S 3 =[ABBABAAB], S 4 =[ABBABAABBAABABBA], … N layers =2 n d Sn =2d Sn-1

4. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Etching solution: HF/EtOH=30/70 Silicon wafer: p+ type, orientation, 8-12 m cm resistivity Calibration curves Bruggemann Model A B n A =1.3, d A = 0.135 m n B =1.96, d B = 0.90 m

5. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Normal incidence reflectivity Optical Spectrum Analyser (OSA)

6. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Variable angle reflectivity S 6 Partial FBG Width = 70 nm -30°<  <30° S 7 Partial FBG Width = 90 nm -30°<  <30°

7. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Thue-Morse sensing Number of layers High porosity layer Low porosity layer Peak wavelength Device thickness 6481 %56 %1030 nm 7.2 m

8. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Thank you for your attention