Tektronix KEITHLEY 3765 User Manual
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Tektronix KEITHLEY 3765 User Manual

Tektronix KEITHLEY 3765 User Manual

Hall effect card
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  • Page 1 T h e t e s t & me a s u r e me n t e q u i p me n t y o u n e e d a t t h e p r i c e y o u w a n t . A l l t e s t I n s t r u me n t s , I n c .
  • Page 2 www.tek.com/keithley Model 3765 Hall Effect Card User’s Manual 3765-900-01 Rev. A / August 2017 *P3765-900-01A* 3765-900-01A...
  • Page 3 Model 3765 Hall Effect Card User's Manual © 2017, Keithley Instruments Cleveland, Ohio, U.S.A. All rights reserved. Any unauthorized reproduction, photocopy, or use of the information herein, in whole or in part, without the prior written approval of Keithley Instruments is strictly prohibited. These are the original instructions in English.
  • Page 4 Safety precautions The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used with nonhazardous voltages, there are situations where hazardous conditions may be present. This product is intended for use by personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury.
  • Page 5 For safety, instruments and accessories must be used in accordance with the operating instructions. If the instruments or accessories are used in a manner not specified in the operating instructions, the protection provided by the equipment may be impaired. Do not exceed the maximum signal levels of the instruments and accessories. Maximum signal levels are defined in the specifications and operating information and shown on the instrument panels, test fixture panels, and switching cards.

  • Page 6: Table Of Contents

    Table of contents Introduction ....................... 1-1 Your Hall Effect card ......................1-1 System switch / multimeter card compatibility ..............1-2 Extended warranty ....................... 1-2 Series 3700A documentation ....................1-3 Contact information ......................1-3 General information ......................1-4 Specifications ........................1-4 Installation and connections ..................
  • Page 7 Table of contents Model 3765 Hall Effect Card User's Manual Resistivity selection ......................3-40 Selecting the resistivity setup ....................3-41 Input characteristics ........................ 3-41 Equivalent input circuits ......................3-41 Resistivity setup criteria ......................3-42 Typical Applications ....................4-1 Introduction .......................... 4-1 Recommended equipment ......................

  • Page 8: Introduction

    Section 1 Introduction In this section: Your Hall Effect card ..............1-1 System switch / multimeter card compatibility ......1-2 Extended warranty ..............1-2 Series 3700A documentation ........... 1-3 Contact information ..............1-3 General information ..............1-4 Specifications ................1-4 Your Hall Effect card The Model 3765 Hall Effect Card is a 4x5 matrix card designed for use in the Model 3706A System Switch/Multimeter.

  • Page 9: System Switch / Multimeter Card Compatibility

    Section 1: Introduction Model 3765 Hall Effect Card User's Manual The 3765 has low-leakage reed relays with actuation times as low as 1 ms that let you use the 3765 to make accurate, low-current measurement applications. The 3765 output can be connected to the 3706A DMM through the backplane relay.

  • Page 10: Series 3700A Documentation

    Model 3765 Hall Effect Card User's Manual Section 1: Introduction Series 3700A documentation Complete documentation for the Series 3700A System Switch/Multimeter instruments is available at Keithley Instruments website (http://www.tek.com/keithley). The following is a list of available documentation. Document Document name Content description number 3700AS-903-01...

  • Page 11: General Information

    Section 1: Introduction Model 3765 Hall Effect Card User's Manual General information General ratings for the Model 3765 are listed in the following table. Category Specification Voltage rating* 30 V Current rating 100 mA Input and output connections Current source input female triaxial cables Sample inputs for female triaxial cables Current monitor female BNC Measurement output spring loaded terminals...

  • Page 12: Installation And Connections

    Section 2 Installation and connections In this section: Handling precautions ............... 2-1 Unpack and inspect the instrument .......... 2-1 Card connectors ............... 2-2 Card installation ............... 2-2 Recommended cables and connectors ........2-4 Web browser support ............... 2-5 Handling precautions Make sure to handle the Model 3765 carefully.

  • Page 13: Card Connectors

    Section 2: Installation and connections Model 3765 Hall Effect Card User's Manual Card connectors You can make signal input and output connections with the triaxial and BNC connectors on the card. The locations for each channel input and the card output are located outside of the card. Connections are dependent on the application being performed.
  • Page 14 Model 3765 Hall Effect Card User's Manual Section 2: Installation and connections To install a switching card into the instrument mainframe: 1. Turn the instrument off and disconnect the power line cord and any other cables connected to the rear panel. 2.

  • Page 15: Recommended Cables And Connectors

    Section 2: Installation and connections Model 3765 Hall Effect Card User's Manual Changing guarding and jumper settings is required before connecting the test system for completing most measurements. For more information see 3765 Guarding methods (on page 3-30). Recommended cables and connectors Below is a list of recommended cables and connectors for use with the Model 3765 Hall Effect Card.

  • Page 16: Web Browser Support

    Model 3765 Hall Effect Card User's Manual Section 2: Installation and connections Web browser support Web browser support for the Model 3765 Hall Effect Card is not supported with the 3706A Switch System/DMM. 3765-900-01 Rev. A / August 2017...

  • Page 17: Operation

    Section 3 Operation In this section: Introduction ................3-1 Safety hazards ................. 3-2 Channel specifiers ..............3-3 Cable preparation ..............3-13 van der Pauw sample connections ......... 3-16 Bar-type sample connections ..........3-19 Bridge and parallel-piped type sample connections ....3-25 Shorting the current monitor output ........

  • Page 18: Equipment In The Test System

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Equipment in the test system Equipment in the test system includes: Instrument Description Recommend Keithley models Current source Applies the current to the sample under test. 6221 current source Picoammeter Measures the current through the sample 6485 or 6487 picoammeter under test.

  • Page 19: Channel Specifiers

    Model 3765 Hall Effect Card User's Manual Section 3: Operation Follow these recommendations before and after applying power to the equipment: 1. Do not exceed the 3765 maximum allowable signal level as defined in the specifications. 2. Do not exceed the 3765 maximum common mode voltage of 30 V as defined in the specifications.
  • Page 20 Section 3: Operation Model 3765 Hall Effect Card User's Manual Hall Effect card matrix The 3765 is organized into a five-by-four matrix, as shown in the next figure. Each intersection of a column and row is called a crosspoint and is designated by a small circle on the diagram. You can connect a row to a column by closing the appropriate crosspoint.
  • Page 21 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 3: 3765 Matrix configuration When making low resistivity measurements, voltage sensitivity and noise may be critical. A nanovoltmeter may be required to achieve optimal performance. The nanovoltmeter can be connected to J7 (external terminal block) pins 5 and 4.
  • Page 22 Section 3: Operation Model 3765 Hall Effect Card User's Manual The 3706A DMM can measure voltage directly from the 3765 card. Closing the backplane relay 911, routes HI and LO signals onto the backplane; allowing the DMM to measure the voltage. The 3765 has a 12 V voltage clamp and a 500 μA current limit.
  • Page 23 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 4: Basic Hall system configuration When making low resistivity measurements, voltage sensitivity and noise may be critical. A nanovoltmeter may be required to achieve optimal performance. The nanovoltmeter can be connected to J7 (external terminal block) pins 5 and 4.
  • Page 24 Section 3: Operation Model 3765 Hall Effect Card User's Manual Figure 5: Connecting a nanovoltmeter 3765-900-01 Rev. A / August 2017...
  • Page 25 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 6: Nanovoltmeter configuration 3765-900-01 Rev. A / August 2017...
  • Page 26 Section 3: Operation Model 3765 Hall Effect Card User's Manual Cable connection for the nanovoltmeter The 2107-4, 2107-30, and 2107-50 cables are recommended for making connections when using the nanovoltmeter. Remove the spade lugs and connect the unterminated end to J7 (external terminal block) pins 5 and 4.
  • Page 27 Model 3765 Hall Effect Card User's Manual Section 3: Operation Analog backplane relay channel specifiers The channels for slots with analog backplane relays are referred to by their slot, backplane, bank, and relay numbers: • Slot: The number of the slot. •...
  • Page 28 Section 3: Operation Model 3765 Hall Effect Card User's Manual Test system The next figure represents a basic configuration of an IEEE-488-based Hall measurement system. A system used primarily for resistivity measurements does not require the electromagnet or magnet power supply. Figure 9: 3765 IEEE 488 test system 3-12 3765-900-01 Rev.

  • Page 29: Cable Preparation

    Model 3765 Hall Effect Card User's Manual Section 3: Operation Cable preparation The necessary cables, wires, and connectors are supplied with the 3765. These cables and wires must be prepared before use as described below. To prevent electrical shock that could cause injury or death, never make or break connections while the equipment is powered on.

  • Page 30: Triaxial Cable Preparation

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Triaxial cable preparation The internal wire conductor must be exposed (stripped) to the proper dimension to ensure correct insertion depth in the connector. Excessive conductor will be exposed if the strip length is too long, which will cause an electrical shock hazard to equipment and personnel.

  • Page 31: Coaxial Cable Preparation

    Model 3765 Hall Effect Card User's Manual Section 3: Operation Coaxial cable preparation In situations like bar and bridge samples, the picoammeter must be connected directly to the sample using a 4802 coaxial cable. To prepare the 4802 coaxial cable: 1.

  • Page 32: Van Der Pauw Sample Connections

    Section 3: Operation Model 3765 Hall Effect Card User's Manual van der Pauw sample connections The next figure shows typical connections for measurements made using the van der Pauw method. Figure 11: Connections for van der Pauw Samples 3-16 3765-900-01 Rev. A / August 2017...
  • Page 33 Model 3765 Hall Effect Card User's Manual Section 3: Operation To make the connections: 1. Connect the current source input connector of the 3765 to the output (Ext) connector of the current source using a 7078-TRX triaxial cable. This setup assumes that the guarded source input configuration is to be used. See Guardng methods (on page 3-30) for more information on guarding.
  • Page 34 Section 3: Operation Model 3765 Hall Effect Card User's Manual Figure 12: Equivalent circuit for van der Pauw connections 3-18 3765-900-01 Rev. A / August 2017...

  • Page 35: Bar-Type Sample Connections

    Model 3765 Hall Effect Card User's Manual Section 3: Operation Bar-type sample connections The next figure shows typical connections for a measurement made using the bar-type method. To make the connections: 1. Connect the current source OUTPUT (Ext) connector using a 7078-TRX triaxial cable. This setup assumes that the guarded source input configuration is to be used.

  • Page 36: Hall Voltage Measurements For Bar-Type Samples

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Hall voltage measurements for bar-type samples Use the basic scheme, shown in the next figure, for Hall voltage measurements on bar-type samples. Figure 13: Connections for Hall Voltage measurements of Bar Type samples 3-20 3765-900-01 Rev.
  • Page 37 Model 3765 Hall Effect Card User's Manual Section 3: Operation To make connections: Connect the sample to the sample inputs, as shown in the next figure. Use the supplied 7078-TRX triaxial cables. See triaxial cable preparation (on page 3-14) for instructions. When programming the current source, you have the option to use the front panel or to do so remotely.

  • Page 38: Resistivity Connections For Bar-Type Samples

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Figure 14: 3765 Hall voltage circuit equivalient Resistivity connections for bar-type samples Except for the DMM connection, resistivity connections of bar-type samples are comparable to Hall voltage. As shown in the next figure, DMM-LO (pin 2 or 9 of DB-15) should be connected to terminal 4 of the J7 terminal strip, and DMM-HI (pin 1 of DB-15) should be connected to terminal 5.
  • Page 39 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 15: Connections for resistivity measurements of bar-type samples 3765-900-01 Rev. A / August 2017 3-23...
  • Page 40 Section 3: Operation Model 3765 Hall Effect Card User's Manual The next figure shows an equivalent circuit of the test configuration. Figure 16: Resistivity measurements of bar-type samples 3-24 3765-900-01 Rev. A / August 2017...

  • Page 41: Bridge And Parallel-Piped Type Sample Connections

    Model 3765 Hall Effect Card User's Manual Section 3: Operation Bridge and parallel-piped type sample connections To make 6- and 8-contact sample connections using the 3765, follow the steps below. Examples of these connections are shown in 6-contact samples (on page 3-26) and 8-contact samples (on page 3- 28).
  • Page 42 Section 3: Operation Model 3765 Hall Effect Card User's Manual Connections for 6-contact samples are shown in the figures below. Figure 17: Connections for 6-contact samples 3-26 3765-900-01 Rev. A / August 2017...
  • Page 43 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 18: 3765 6-contact sample equivalent circuit 3765-900-01 Rev. A / August 2017 3-27...
  • Page 44 Section 3: Operation Model 3765 Hall Effect Card User's Manual Connections for 8-contact samples are shown in the figures below. Figure 19: Connections for 8-contact samples 3-28 3765-900-01 Rev. A / August 2017...
  • Page 45 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 20: 3765 8-contact sample equivalent circuit 3765-900-01 Rev. A / August 2017 3-29...

  • Page 46: Shorting The Current Monitor Output

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Shorting the current monitor output To accurately measure the sample excitation current, you can set up a system with a 6485 or similar picoammeter. As an alternative, a system without a picoammeter can be used by placing the 4851 BNC shorting plug on the current monitor output jack in place of the picoammeter connecting cable.
  • Page 47 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 21: Unguarded circuit example The sample resistance and cable impedance form a voltage divider that attenuates the sample voltage: 3765-900-01 Rev. A / August 2017 3-31...

  • Page 48: Current Source Input Guarding

    Section 3: Operation Model 3765 Hall Effect Card User's Manual To keep the leakage resistance error under 0.1%, the leakage resistance must be at least one thousand times the sample resistance. For low to medium resistivity samples, the leakage resistance is high enough to have minimal effects.
  • Page 49 Model 3765 Hall Effect Card User's Manual Section 3: Operation Guarding jumpers As shown in the next figure, the current source input for either unguarded or guarded operation is set up by two jumpers. The jumper configurations shown at the top of the diagram indicate which of the two configurations apply.
  • Page 50 Section 3: Operation Model 3765 Hall Effect Card User's Manual Changing jumper settings The 3765 default setup is for is guarded configuration. To change or verify the positions of the jumpers: 1. Turn off the 3700A power, and unplug the power line cord. 2.
  • Page 51 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 24: Changing jumper settings 3765-900-01 Rev. A / August 2017 3-35...
  • Page 52 Section 3: Operation Model 3765 Hall Effect Card User's Manual Unguarded connections Use the procedure below to connect the current source to the 3765 using the following figure as a guide. Note that this configuration should only be used with the card in the low resistivity mode, as discussed in Resistivity selection (on page 3-40).
  • Page 53 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 25: Unguarded connections equivalent circuit 3765-900-01 Rev. A / August 2017 3-37...

  • Page 54: Sample Input Guarding

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Guarded connections The current source input should be guarded when the card is in high-resistivity mode. The next figure shows the basic connections, which are outlined as follows. 1. Connect the 7078-TRX triaxial cable between the triaxial end on the adapter and the 3765 current source input.
  • Page 55 Model 3765 Hall Effect Card User's Manual Section 3: Operation Figure 27: Shield removal 3765-900-01 Rev. A / August 2017 3-39...

  • Page 56: Front Panel Current Source Programming

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Front panel current source programming The inner shield of the triaxial connector can be connected to output low (to be compatible with the Keithley 220 current source) or cable guard of a current source. Output low is the default connection. The current source output must be off in order to change the inner shield setting.

  • Page 57: Selecting The Resistivity Setup

    Model 3765 Hall Effect Card User's Manual Section 3: Operation Selecting the resistivity setup The sample inputs can be programmed for low- or high-resistivity by controlling the state of crosspoint 4,5 (row 4, column 5). To select high-resistivity, close crosspoint 4,5; to select low resistivity, open crosspoint 4,5.

  • Page 58: Resistivity Setup Criteria

    Section 3: Operation Model 3765 Hall Effect Card User's Manual Resistivity setup criteria The setup depends on the resistivity of the sample under test. Some experimentation may help to obtain the best choice with a particular sample. For sample resistances above 1 MΩ, input loading can occur due to accuracy degradation. When measuring samples above 1 MΩ, you should always use the high-resistivity setup.
  • Page 59 Model 3765 Hall Effect Card User's Manual Section 3: Operation The next figure illustrates noise voltage versus actual sample resistance. The tangential lines are theoretical limits given the thermal (Johnson) noise resistance. If the sample temperature is reduced to liquid nitrogen levels (77 K or below), the noise, due to sample resistivity, has improved the limit. Below sample resistances of 10 kΩ, lowering the temperature will not significantly improve the noise performance because the instrument noise dominates at room temperature.

  • Page 60: Typical Applications

    Section 4 Typical Applications In this section: Introduction ................4-1 Hall Effect Test Suite software ..........4-2 Conventions and principles ............4-5 van der Pauw resistivity measurements ......... 4-10 Hall voltage measurements ............ 4-14 Measuring bar-type samples ..........4-18 Measuring bridge and parallel-piped-type specimens .... 4-30 Introduction This section briefly discusses Hall effect, Hall conventions, and gives some typical measurement examples for the Model 3765.

  • Page 61: Hall Effect Test Suite Software

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Hall Effect Test Suite software The 3765 has a Hall Effect Test Suite project for the applications in this section. Using the Hall Effect Test Suite, you can easily input the instruments, source settings, measure settings, and test type in the Test Input Parameters window of the Hall Effect Test Suite GUI.

  • Page 62: Hall Effect Test Suite Instrument Configuration

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Hall Effect Test Suite instrument configuration To configure the instruments needed to complete a test: 1. Select Instruments from the toolbar. 2. Select Configure. 3. Select the model of the instrument you are connecting. 4.

  • Page 63: Hall Effect Test Suite Test Input Parameters

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Hall Effect Test Suite test input parameters After you have configured the instruments in your test setup and tested the connections, you can run your desired tests. To run the tests: 1.

  • Page 64: Hall Effect Test Suite Sample Results

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Hall Effect Test Suite sample results An example of test results is shown below. This graphic illustrates the given results for a van der Pauw test using the Hall Effect Test Suite. Figure 34: Hall Effect Test suite sample results Conventions and principles The following paragraphs discuss Hall effect sign and sample terminal conventions, basic Hall effect...

  • Page 65: Measurement Units

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Measurement units The table below summarizes generally accepted units of measure. Quantity Symbol Units Sample dimensions L, t, w, d Potential difference Charge Carrier concentration n, p Drift mobility µ...

  • Page 66: Terminal Conventions

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Figure 36: Hall effect sign conventions for p-type materials Terminal conventions In the case of van der Pauw resistivity measurements, a current is applied between two terminals, while the voltage is measured between the two opposite terminals, as shown in the next figure. A total of eight such measurements are taken with each possible terminal and current convention.
  • Page 67 Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 37: Resistivity measurement conventions 3765-900-01 Rev. A / August 2017...
  • Page 68 Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications The connections for Hall voltage measurements are shown in the next figure. Current is applied and voltage is measured across the diagonal of the sample. Eight measurements are necessary, both with positive and negative current and positive and negative magnetic flux.

  • Page 69: Basic Hall Effect Principles

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Basic Hall Effect principles For the following discussion, refer to the basic sample configuration shown in the previous figure, Hall effect sign conventions for n-type materials. If a current, l = J / A, is applied across the length of the sample, voltage is developed across that sample.
  • Page 70 Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Figure 39: Measurement configuration for resistivity and Hall voltage measurements 3765-900-01 Rev. A / August 2017 4-11...

  • Page 71: Van Der Pauw Resistivity Measurement Test Procedure

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual van der Pauw resistivity measurement test procedure Use the following procedure to measure parameters necessary to calculate sample resistivity. The procedure assumes that the sample has been stabilized at the desired operating temperature and will remain at that temperature throughout the tests.

  • Page 72: Van Der Pauw Resistivity Measurement Resistivity Calculations

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications *Only those crosspoints shown can be closed for a specific measurement, except 4,5 which controls the input configuration for low- or high-resistivity samples. van der Pauw resistivity measurement resistivity calculations Once the voltages and current through the sample have been measured, the resistivity can be calculated as follows.

  • Page 73: Hall Voltage Measurements

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual A plot of this function is shown in the figure below. Figure 40: Plot of f versus Q Hall voltage measurements The following paragraphs discuss Hall voltage measurements on van der Pauw type samples. 4-14 3765-900-01 Rev.

  • Page 74: Hall Voltage Measurement Test Configuration

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Hall voltage measurement test configuration The sample test configuration can be used to measure the parameters necessary to calculate Hall coefficients. In addition to the equipment shown, a suitable magnet or electromagnet will be necessary to generate the required magnetic field.

  • Page 75: Hall Voltage Measurement Test Procedure

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Hall voltage measurement test procedure Use the procedure below to measure data that is necessary to calculate Hall coefficients. Note that the sample should be stabilized at the desired temperature before and during the tests. Also, the flux density magnitude must be kept constant during the measurements.

  • Page 76: Hall Voltage Measurement Coefficient Calculations

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Voltage Flux Crosspoints closed Current Voltage designation (row, columns)* applied measured between between *Only those crosspoints shown can be closed for a specific measurement, except 4,5 which controls card input configuration for low or high resistivity samples.

  • Page 77: Hall Voltage Measurement Mobility Calculation

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Where: • are Hall coefficients in cm • is the sample thickness in cm. • B is the magnetic flux density in gauss. • I is the current measured by the picoammeter in amperes. •...
  • Page 78 Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Figure 42: Test configuration for Hall voltage measurements of bar-type samples 3765-900-01 Rev. A / August 2017 4-19...
  • Page 79 Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 43: Test configuration for Hall voltage measurement of bar samples The crosspoints that must be closed depend on whether resistivity or Hall voltage measurements are to be taken. The Crosspoint configurations for bar measurements (on page 4-27) table summarizes which crosspoints to close for each type of measurement.

  • Page 80: Determining Potentiometer Values For Bar-Type Measurements

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Determining potentiometer values for bar-type measurements The loading effects of the DMM and potentiometer can affect the accuracy of both low- and high- resistivity measurements. The table below summarizes recommended potentiometer values along with nominal errors.
  • Page 81 Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 44: Hall bar equivalent circuit 4-22 3765-900-01 Rev. A / August 2017...

  • Page 82: Measuring High Resistivity Of Bar-Type Samples

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Measuring high resistivity of bar-type samples In order to minimize loading errors, the equivalent resistance seen by the buffers must be as low as possible; also, the DMM input resistance must be substantially higher than the equivalent resistance seen at its input.

  • Page 83: Bar Resistivity Measurements

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 46: Equivalent potentiometer circuit, low resistivity Bar resistivity measurements Use the basic procedure below to make the necessary measurements to determine resistivity of bar- type samples. This procedure assumes that the sample temperature is held to the constant necessary temperature throughout the test.
  • Page 84 Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Figure 47: Test configuration for Hall voltage measurements of bar-type samples 3765-900-01 Rev. A / August 2017 4-25...

  • Page 85: Hall Voltage Measurements Of Bar-Type Samples

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Hall voltage measurements of bar-type samples The following procedure assumes that the sample is held stable at the preferred temperature throughout the tests, and that the applied magnetic flux is also held constant at the desired density. To measure Hall voltage: 1.

  • Page 86: Crosspoint Configurations For Bar Measurements

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Figure 48: Test configuration for Hall voltage measurements of bar-type samples Crosspoint configurations for bar measurements Measurement Closed crosspoints (row, column) Resistivity Hall voltage 3765-900-01 Rev. A / August 2017 4-27...

  • Page 87: Calculations For Bar-Type Samples

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Calculations for bar-type samples Bar-type resistivity calculations The resistivity of the sample is related to the voltage measurements as follows: Where: • is the voltage measured by the DMM. •...
  • Page 88 Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Bar-type mobility calculations Once the resistivity and Hall voltages are known, the mobility, µ, can be determined as follows: Where: • µ is the mobility in cm / Vs. •...

  • Page 89: Measuring Bridge And Parallel-Piped-Type Specimens

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 49: Bar sample dimensions Measuring bridge and parallel-piped-type specimens The fundamental procedures for measuring 6- and 8-contact bridge and parallel-piped-type specimens are discussed in the following paragraphs. 4-30 3765-900-01 Rev.

  • Page 90: Bridge And Parallel-Piped-Type Test Configurations

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Bridge and parallel-piped-type test configurations The first of the following figures shows the test setup for 6-contact specimens, and the setup for 8-contact samples is shown in the second figure. In both cases, four sample contacts are connected to the sample inputs on the 3765.
  • Page 91 Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 51: Connections for an 8-contact sample 4-32 3765-900-01 Rev. A / August 2017...

  • Page 92: Bridge And Parallel-Piped-Type Resistivity Measurements

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Bridge and parallel-piped-type resistivity measurements Use the basic procedure below to measure parameters for 6- and 8-contact specimens. As always, the sample should be stabilized at the needed temperature both before and during the tests. To measure the 6- and 8-contact specimens: 1.

  • Page 93: Bridge And Parallel-Piped-Type Hall Voltage Measurements

    Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Bridge and parallel-piped-type Hall voltage measurements The following procedure assumes that the sample is held stable at the needed temperature throughout the tests and that the applied magnetic flux is also held constant at the desired flux density.

  • Page 94: Bridge And Parallel-Piped-Type Measurement Calculations

    Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Voltage Flux polarity Crosspoints closed Current between* Voltage between designation (row, column) *Reverse current by programming source for opposite polarity. Voltage Flux polarity Crosspoints closed Current between* Voltage between designation (row,column) *Reverse current by programming source for opposite polarity.
  • Page 95 Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Figure 52: Sample dimensions necessary for calculations Bridge and parallel-piped-type resistivity calculations Two resistivity values, P and P can be calculated as follows: and, 4-36 3765-900-01 Rev. A / August 2017...
  • Page 96 Model 3765 Hall Effect Card User's Manual Section 4: Typical Applications Where: ρ and ρ = resistivity in ohm × cm • is the sample width in cm. • is the sample thickness in cm. • and D are the sample dimensions in cm. •...
  • Page 97 Section 4: Typical Applications Model 3765 Hall Effect Card User's Manual Where: R is the Hall coefficient in cm / C. • is the sample thickness in cm. • B is the flux density in gauss. • I is the current measured by the picoammeter in amperes. •...

  • Page 98: Index

    Index Analog backplane relay channel specifiers • 3-11 Determining potentiometer values for bar-type measurements • 3-21, 4-21 Bar resistivity measurements • 4-24 Bar-type Hall voltage calculations • 4-28 Equipment in the test system • 3-2 Bar-type measurement test configuration • 4-18 Equivalent input circuits •...
  • Page 99 Index Model 3765 Hall Effect Card User's Manual Input characteristics • 3-41 van der Pauw sample connections • 3-16 Installation and connections • 2-1 Introduction • 1-1, 3-1, 3-5, 3-7, 4-1 Web browser support • 2-5 Matrix and test configurations • 3-3 Matrix card channel specifiers •...
  • Page 100 Specifications are subject to change without notice. All Keithley trademarks and trade names are the property of Keithley Instruments. All other trademarks and trade names are the property of their respective companies. Keithley Instruments Corporate Headquarters • 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168 • 1-800-935-5595 • www.tek.com/keithley 3/17...

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