High sensitivity and quantitative magnetic field measurements at 600°C

Abstract

High sensitivity micro-Hall sensors were fabricated using AlGaN∕GaN two-dimensional electron gas heterostructures grown by molecular beam epitaxy for high temperature operation. The room temperature electron mobility and sheet carrier concentration of the heterostructures were 850cm2∕Vs and 7.7×1012cm−2, respectively. The Hall voltage increased linearly with applied magnetic field up to 0.5T for all temperatures in the range of temperature from 20to600°C. A 100μm×100μm Hall device with a magnetic sensitivity of 0.35G∕(Hz)1∕2 at 600°C was used to measure the Curie temperature of NdFeB. The AlGaN∕GaN micro-Hall sensors will find a wide range of applications including high temperature scanning Hall microscopy, monitoring rotating parts in the engines of automobiles as well as space vehicles which are exposed to extreme changes in temperature and radiation.