Lake Shore Cryotronics Measure Ready M91 FastHall, Руководство пользователя, Страница: 48 / 195

38 c
HAPTER
3: Operation
MeasureReady™ M91 FastHall™ Measurement Controller
3.7 Measurement
Structure with
SCPI Commands
3.7.1 Starting a
Measurement The MeasureReady™ M91 FastHall™ measurement controller executes the following
measurements: contact check, resistivity, and Hall measurement. Each time a new
measurement is run, it overwrites the existing measurement data of its type (a con-
tact check will overwrite a contact check, but will not overwrite a resistivity measure-
ment). Cycling power or resetting the instrument will clear all data.
All setup parameters related to running a measurement are contained in the mea-
surement-specific start command. This commands sets parameters such as measure-
ment/excitation settings, safety limits, sample properties, and any other required
inputs needed in calculating the output.
Each command input parameter is designated as either required or optional. For
example, the sample thickness parameter on both the resistivity and FastHall™ com-
mands is listed as an optional parameter. If a thickness is provided, the volumetric
resistivity (
)
cm) and carrier concentration (cm -3 ) are calculated. However, if the
parameter is not specified, the sheet resistance (
)
/
□
) and sheet carrier concentration
(cm -2 ) are calculated. Note that the Hall mobility calculation doesn’t directly depend
on the sample thickness, so it remains unchanged. Details on starting each measure-
ment are provided below.
3.7.1.1 Link Measurements
The purpose of linking within measurements is to easily transfer data between mea-
surements. For consistency, all data passed from the instrument is displayed in com-
mon lab (SI) units. See section 1.2.1 for further information.
This feature is only available for van der Pauw samples
.
Follow the steps below to use linking.
1.
Run a contact check measurement (manual or auto )
CCH:START
The following parameters are used automatically as inputs to resistivity and
FastHall™ when linking is used: excitation type, excitation value, excitation
range, measurement range, current limit, and voltage compliance.
2. Run a resistivity link measurement
RES:START:LINK
The resistivity measurement will automatically pull in the parameters listed in
step 1. The following parameters will are used automatically used as inputs to
FastHall™ linking: resistivity and sample thickness. A contact check must have
been completed prior to running a resistivity link measurement.
3. Run a FastHall link measurement
FAST:START:LINK <enter field value>
The FastHall measurement will automatically pull in the parameters listed in
steps 1 and 2. A contact check measurement must have been completed prior to
running a FastHall link measurement. A resistivity measurement must have been
completed prior to the FastHall link measurement to pull in a resistivity value for
a full Hall analysis.
Only the field value is a required parameter when using the measurement link commands.
All other parameters are either pulled in from previous measurements or set to default
values. Any of the default values can be manually overwritten.