Behavior of Gold-Doped Silicon Substrate under Small- and Large-RF Signal

Abstract

In this paper, small-and large-signal performances of passive devices integrated on high-resistivity, trap-rich and gold-doped silicon wafers are presented and compared through measurements and simulations. The gold-doped silicon substrate was produced starting from standard silicon having a nominal resistivity of 56 Ω.cm. We show that the gold-doped substrate presents high effective resistivity and low losses suitable for RF applications, this has been done by measuring coplanar waveguides, crosstalk, inductors and band pass filter where we saw a similar performances under small signal-measurements. Largesignal measurements of gold-doped substrates show 60 dBm lower harmonic distortion than high-resistivity substrates, and 10 dB lower than trap-rich substrate. A large DC bias dependence on the harmonic distortion induced by the gold-doped substrate is observed. This unexpected behavior is explained using the Fermi level localization in the silicon bandgap for the different DC bias conditions.