Development of the microwave Hall effect technique using an ESR spectrometer and a network analyser

Abstract

An electron spin resonance (ESR) system was modified to conduct microwave Hall effect (MHE) measurements, but the ESR capability of the system was fully retained using interchangeable equipment. An X-band microwave frequency, a square-law detector, and phase-sensitive detection of the ESR signal were utilized during the modification. The ESR cavity was replaced with a bimodal MHE cavity and source modulation was used instead of field modulation. A cancelling channel was added to cancel out the non-ideal power at the secondary mode. A vector network analyser was used to tune the cavity and to measure the mobility of high mobility samples. A bimodal TE112 cylindrical cavity and a TE102 rectangular cavity were designed and constructed, and both gave good results. Silicon semiconductor samples, which had previously been well characterized, were used to calibrate the system and calculate the calibration constants.

Contactless Microwave Hall Effect Transport in ZnSe

“…When a sample is put into the cavity and a magnetic field is applied, the energy of the excited mode is partially transferred to the orthogonal mode and a signal appears on the second port. The information obtained from the characterization of both the empty and the sample loaded cavity allows the determination of the mobility of the sample [7,8,14]. Microwave data are compared with other works [15,16,17] dc data.…”

Measurement of Microwave Electrical Transport Properties

“…Before a dc magnetic field B is applied, the output mode is not excited, that is, E 2 = 0. When an external dc magnetic field is applied, the relationship between the output electric field E 2 and input electric field E 1 is a measure of the microwave Hall mobility µ H (Na et al 1991):…”

The Mechanism of Interfacial CO2 Activation on Al Doped Cu/ZnO

“…Contact-free electrical conductivity measurements under catalytic relevant conditions have been introduced based on the microwave cavity perturbation technique. ,− In contrast to that the contact-free Microwave Hall Effect (MHE) allows one to determine not only the electrical conductivity but also carrier mobility changes. Hence, MHE measurements provide access to the charge carrier concentration, the quotient of the electrical conductivity and the Hall mobility (see eq , experimental part). ,, The experimental setup for the MHE measurements utilizes bimodal microwave cavities which exhibit two orthogonal modes and an external static magnetic field perpendicular to the two electrical modes. The principle of the measurement is based on the fact that one of the two modes is excited by an external microwave source while energy is transferred to the orthogonal mode by the Hall effect induced by the charge carriers of a sample inside the bimodal cavitiy.…”