Design and fabrication of microwave circuits for proposed microwave hall measurements

Abstract

Microwave circuits have a large application base, from biomedical fields to controlling quantum qubits inside a quantum computer. For the purpose of realising quantum systems and building a working quantum computer prototype, these circuits and devices needed to be thoroughly analysed, designed and precisely fabricated. The design and fabrication of these devices become tricky when dealing with high-frequency signals, and thus, this opens some exciting windows to study the effects of high-frequency signals on thin-film samples. The hall measurements are a well-known method to determine the carrier type, carrier concentration and mobility of a material. Measuring the DC hall on a sample requires putting point contacts, which destroys the sample for further use. This thesis tries to measure the Hall effect by a noninvasive method using high-frequency microwave signals. We designed and fabricated a homemade micro-strip circuit using photo-lithography and took measurements on nickel, germanium, graphene and bismuth selenide samples. The results obtained show that the hall field shows a linear increase with the applied magnetic field, and the phase is reversed when the magnetic field direction is reversed.