Nanostructured porous silicon as thick electrical insulator for radio-frequency applications

Nanostructured porous silicon layers are studied for the purpose of their use as electrical insulators between mono‐crystalline silicon substrates and integrated planar radio frequency (rf) devices. The capacitive nature of the layers with a tangent loss lower than 10–2 is demonstrated in the 105–109 Hz range by means of complex impedance measurements and rf regime experiments on micro L –C resonant circuits. Finally, the insulating capabilities of nanostructured porous silicon were evaluated using numerical simulations combined with our experimental data. A minor contribution of the porous silicon residual conductance to the rf energy loss is found. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)