Broadband electrical characterization of macroporous silicon at microwave frequencies

✍ Scribed by Contopanagos, H. ;Pagonis, D. N. ;Nassiopoulou, A. G.

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 274 KB
• Volume: 205
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200780105

✦ Synopsis

Abstract

Macroporous silicon layers with randomly distributed vertical cylindrical pores of average diameter 120 nm were fabricated on selected areas on a p^+^ (resistivity 5 mΩcm) silicon substrate by anodization in HF~x~ethanol solution. The thickness of the layers was 50 μm and they are intended for use as RF isolation micro‐plates for on‐chip passive devices operated at microwave frequencies. In this respect, we present in this work results of their electrical characterization in the 40 MHz‐7 GHz frequency range using a macroscopic platform, where the die containing the porous silicon layer on the highly doped Si substrate is inserted directly underneath a microstrip line. The highly doped Si substrate used acts as a lossy metal ground for the microstrip. We measured and simulated the scattering parameters of the system using a finite‐element full‐wave electromagnetic solver. We have chosen a broad frequency band extending from 40 MHz up to 7 GHz, beyond the first harmonic of the transmission line. By identifying measured and simulated S‐parameters over the whole frequency band we extract both geometrical characteristics of the measurement set‐up not accessible to direct measurements and the complex permittivity of porous silicon. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)