Millimeter wave complex refractive index,complex dielectric permittivity and loss tangent of extra high purity and compensated silicon

Single crystal high resistivity (11,000 ohm-cm) boron doped silicon was found to exhibit lowest absorption loss at room temperature (25 C) in the entire millimeter wave region. At 140 GHz it's loss tangent value is as low as 40 microradians. The study of dielectric properties of silicon as a function of resistivity reveals that the low frequency free carrier absorption present in all silicon (and other semiconductors) vanishes with increasing resistivity. It is then possible to use such a silicon in substrate applications in microwave integrated circuitry. The unique broadband dispersive Fourier transform spectroscopic technique was utilized for these measurement.