The Microwave Hall Effect

TL;DR

This paper introduces a contactless microwave technique using an X-band waveguide to measure the Hall effect in semiconductor wafers, providing a simple, non-resonant method for determining mobility and resistivity.

Contribution

It presents a novel microwave apparatus that measures the Hall effect without contacts or resonant cavities, enabling easier and contactless characterization of semiconductor properties.

Findings

Measured mobilities ranged from 270 to 3000 cm²/(V·s).

The microwave Hall signal is linear with magnetic field and reverses phase when the field is reversed.

Resistivity can be determined from microwave reflection measurements.

Abstract

This paper describes a simple microwave apparatus to measure the Hall effect in semiconductor wafers. The advantage of this technique is that it does not require contacts on the sample or the use of a resonant cavity. Our method consists of placing the semiconductor wafer into a slot cut in an X-band (8 - 12 GHz) waveguide series tee, injecting microwave power into the two opposite arms of the tee, and measuring the microwave output at the third arm. A magnetic field applied perpendicular to the wafer gives a microwave Hall signal that is linear in the magnetic field and which reverses phase when the magnetic field is reversed. The microwave Hall signal is proportional to the semiconductor mobility, which we compare for calibration purposes with d. c. mobility measurements obtained using the van der Pauw method. We obtain the resistivity by measuring the microwave reflection coefficient of the sample. This paper presents data for silicon and germanium samples doped with boron or phosphorus. The measured mobilities ranged from 270 to 3000 cm2 /(V-sec).