Design of a microwave system for measuring dark and photo-conductivity of semiconductors

The semiconductor industry is evolving with new emerging semiconductor materials. Researchers and engineers constantly test and analyse these new materials for their conductivity to further develop this technology. The most traditional method of testing these has been through soldering electrical contacts onto the material. However, this is time consuming. The microwave probe technique used in this thesis is robust and uses relatively easy setup to analyse the electronic properties of the samples. The semiconductor materials are simulated in a rectangular open waveguide and cavity resonator. Different samples with varying conductivity, dielectric constant and sample thickness are probed to measure microwave absorption. Real photovoltaic samples, OPV, silicon, cadmium telluride (CdTe) and gallium arsenide (GaAs) are simulated for their dark and photoconductivity by changing their doping. For dark conductivity simulations, GaAs has the highest conductivity and power absorption of 23%, and OPV has the lowest conductivity and power absorption of 1.5% for low doping. For photoconductivity simulations, the proposed cavity model worked only for low conductivity samples such as OPV, and it has the capacity to absorb a maximum power of 6%. Silicon, CdTe and GaAs were simulated in open waveguide as they were shorting the cavity due to high reflection. GaAs absorbs a maximum power of 35%, silicon absorbs 14% and CdTe absorbs 9%. These results indicate that the proposed design is suitable for probing low conductivity semiconductor materials.