Lake Shore Cryotronics Measure Ready M91 FastHall, User Manual

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4 CHAPTER 1: Introduction
MeasureReady™ M91 FastHall™ Measurement Controller
1.4 Fields of Study The M91 FastHall™ measurement controller, using only a DC field and patented tech-
nology base on reverse field reciprocity theorem, provides Hall measurements to
facilitate the broadest range of research applications. The M91 coupled with the
MeasureLINK™-MCS software for variable temperature and variable field-dependent
magnetotransport measurements provides a means to understand fundamental pro-
cesses in solid state physics and materials science.
1.4.1 Photovoltaic and
Thermoelectric
Applications Photovoltaic (solar cell) and thermoelectric materials are often characterized by low
mobilities. This characteristic makes them difficult or impossible to measure using
traditional DC field Hall methods. The M91 allows measurement of these materials
with only a DC field. Eliminating the requirement for AC fields with van der Pauw
samples, Hall measurements can be performed on a wide range of magnet systems.
The magnet configuration can be chosen based on material and sample consider-
ation. In previous systems using AC fields, the measurements were difficult or even
impossible to use with superconducting magnets or permanent magnets.
1.5 Hall Effect
Measurements Mobility is one of the most important and commonly derived electronic transport
properties of semiconductor materials. The mobility can often be directly related to
the performance of the material in an electronic device. When measured over a range
of temperatures, the change in mobility provides insight into the transport
mechanism of the material. Measuring the mobility in samples from a material that
was produced by different methods yields information to grade material
performance as an electronic device and to optimize production methods.
Hall measurement systems use a material’s Hall effect to determine Hall mobility. The
Hall measurement is also used to determine the associated properties of carrier
concentration, resistivity, and carrier type.
The MeasureReady™ M91 FastHall™ measurement controller can provide a full
range of Hall measurements on both Hall bar and van der Pauw samples. It can
perform full standards-based measurements when necessary, or a smaller subset
when desired. The traditional Hall effect may be the only measurement needed when
measuring well-behaved semiconductors. Other methods are used to determine
mobility especially when the mobility is low or hard to derive.