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Research project

Semi-insulating Silicon substrates for high frequency integrated circuits

Project overview

We demonstrate the ability of deep level doping to reduce the substrate losses in coplanar waveg-uides and spiral inductors. Room temperature resistivity of Au doped Czochralski-Si increases from 50 Ωcm for n-type Si to 100 kΩcm for Au doped Si and temperature dependent Hall measurements show a six order increase in resistivity at lower temperatures which is entirely due to a decrease in free carrier concentration. The mobility is not affected and is determined by lattice scattering only. The resistivity follows theoretical models demonstrating that nearly 100% of the doped Au is electrically active. Coplanar waveguides show a reduction in attenuation at 67GHz from 0.88 dB/mm to 0.30 dB/mm. Spiral inductors fabricated in the compensated substrates show a 50% improvement in quality-factor with respect to high resistivity float zone wafers demonstrating the use of these substrates for integrated passive devices.


Lead researcher

Professor Kees De Groot


Research interests

  • Radio-Frequency and Microwave Devices
  • 2 dimensional Transition Metal Dichalcogenides  Transistors
  • Smart Radiative Cooling and RF control of smart glass using metal oxides such as Al-doped ZnO and W-doped VO2
Connect with Kees

Research outputs