Zero- & Low-Field Transport Detection System

摘要

A sensing apparatus for detecting and determining the magnitude of a static magnetic field has a first set of coils capable of producing a sweeping, quasi static, magnetic field when driven by a direct current and a second set of coils, for magnetic field modulation, positioned between the first set of coils capable of producing a low-frequency (audio), oscillating magnetic field when driven by an oscillating current. The magnetic fields induce a current through the semiconductor device which sampled to identify changes as a function of sweeping, quasi static magnetic field. To create an apparatus for detecting and identifying atomic scale defects in fully processed devices, a radio frequency circuit with a resonant component is added which provides an oscillating electromagnetic field in a direction perpendicular to that of the static magnetic field produced by the first set of coils.

主权项

1. A sensing apparatus for detecting and determining the magnitude of a static magnetic field, the apparatus comprising;
a first set of coils capable of producing a sweeping, quasi static, magnetic field when driven by a direct current; a second set of coils, for magnetic field modulation, positioned between the first set of coils capable of producing an oscillating magnetic field when driven by an oscillating current; a precision, bipolar current controller which drives current through the first set of coils to create a linearly sweeping magnetic field; a signal generator which drives an oscillating current through the second set of coils to create an oscillating magnetic field to modulate the field produced by the first set of coils; a voltage biased, semiconducting device with a known, low magnetic field magnetoresistance properties positioned in between both sets of coils and having a semiconducting device current; an analog front end which conditions the semiconducting device current before being sampled; an analog-to-digital converter which samples the conditioned semiconducting device current; and a signal processing unit capable of demodulating the conditioned sampled semiconducting device current and recording changes in this signal as a function of sweeping, quasi static magnetic field.