2
CHAPTER 1:
Introduction
MeasureReady™ M91 FastHall™ Measurement Controller
1.2 Overview
The M91 FastHall™ measurement controller is a revolutionary, all-in-one instrument
that delivers significantly higher levels of precision, speed, and convenience to
researchers involved in the study of electronic materials.
Featuring Lake Shore’s patented* new FastHall™ measurement technique, the M91
fundamentally changes the way the Hall effect is generated and measured by elimi-
nating the need to switch the polarity of the applied magnetic field during the mea-
surement. This breakthrough results in faster and more accurate measurements,
especially when using high field superconducting magnets or when measuring very
low mobility materials.
*Protected by US patent number 9797965. Other patents pending.
FIGURE 1-1
FastHall vs. conventional Hall measurement time
Conventional Hall
FastHall
™
Time (s)
1.3 s
114 s
FastHall vs. conventional Hall measurement time of an IGZO sample
1.2.1 Optimization
The M91 provides an automatic method to optimize the setup and measurement
parameters for your material, which can then be used in all subsequent measure-
ments. This is based on finding a contact check result with a correlation coefficient
greater than 0.9999 on all four contacts. The optimization method allows the user to
rapidly find the proper excitation value and settle time for a sample without a lengthy
manual trial and error step. Setup parameters are then used in subsequent resistivity
and FastHall™ setups, but only if linking mode is enabled (see SCPI Command
FASThall[:VDP]:STARt:LINk
). The optimization method can also be used in
measurements where the sample parameters may change during the measurement,
for instance, in variable temperature measurements. The user can bypass the optimi-
zation method and manually select all desired operating parameters.
The Link mode uses setup parameter information from the previously-run contact
check and/or resistivity measurement so that the user does not have to manually
enter these parameters for a resistivity or FastHall™ measurement. Link mode only
applies to configurations for van der Pauw samples. Manual mode allows the user to
have full control over all of the input parameters. The optimization method runs inde-
pendent of a contact check sequence, and it selects the optimum excitation type,
value, range and settle time for the user. Link mode is used to either pass the parame-
ters from contact check to a resistivity measurement, or to pass the parameters from
contact check and/or resistivity measurement to a FastHall™ measurement.
1.2.2 Single Instrument
Traditional Hall effect measurement systems (HMS) provide basic electrical measure-
ment instrumentation combined with a generic switch unit to measure sample resis-
tivity and Hall voltages. But they must also rely on separate PC-based software to
perform pre- and post-processing calculations in order to ultimately derive the physi-
cal parameters of carrier type, carrier concentration, mobility, and the Hall coefficient
that researchers need to know. The M91 FastHall™ measurement controller com-
bines all of the necessary HMS functions into a single instrument, automating and
optimizing the measurement process, and directly reporting the desired parameters.
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