ABBESS®

Instruments and Systems
for Developing Leading Technologies, Industrial Methods and Processes

If you have any questions, need pricing, or custom configurations, please call
Phone: (508) 881-8811, FAX: (508) 881-4884
Toll Free: (800) 958-8886

Sales to the US and Canada ONLY
most items controlled by US Dept of State under ITAR or require US Commerce Dept. license.

AC and DC Hall Effect and Resistivity Measurement System


This is a modular AC and DC Hall Effect and Resistivity Measurement System design that allows users to purchase the elements that they need and/or can afford. If you have parts that you would like to have built into a system, we can do that. Our goal is to provide the customer what they require.

This Hall measurement system can be used for the measurement of semiconductor devices. This system can do both simple Hall measurements to determine carrier concentration and mobility in samples such as GaAs and SiC as well as more complex measurements where you want to perform magneto-transport measurements on bipolar junction transistors. This system can also provide you the ability to do photo-hall measurements where the sample is illuminated by a light source ( visible to near IR wavelengths).

The elements are as follows:

  • Variable Temperature Cryostat CTC-9 and Temperature Controller, Custom designed coldfinger, electrical feed throughs and sample mounting, and Quick sample access (no tools needed) tail section with 2 standard quartz windows. Cryostat is able to be rotated through angles between 0 and 90 degrees around a single axis
  • 4” dia. variable Gap, water cooled, DC 1.2 Tesla Electromagnet and computer controllable Power Supply with computer controllable zero crossing current reversing option
  • AC .15 Tesla Modulation coils and Power Supply
  • Lock-in Amplifier 120 kHZ or 250 kHZ sensitive to 10E-8 Amp/Volt
  • Hall Effect Magnetometer for field measurement with analog output to computer A/D Input and/or lock-in input, Hall sensor mounted on cryostat.
  • Nanovoltmeter
  • Voltage/current source
  • Abbess Switching Matrix, Computer controlled for sample contact Switching Matrix 6*12 leads=72 gold/silver contact relays
  • System standwith wheels and leveling feet and platform for cryostat handling(rotation and sample loading-as shown below)
  • Computer and user modifiable Lab-View 6.1 based or MS-Visual Basic Control Software to perform the following tests with respect to the change of magnet field, temperature, applied voltage, and current.
    1. Resistivity
    2. Hall Coefficient
    3. Carrier concentration and mobility
    4. Carrier type (P or N type)

The system is designed to include IEEE-488 interface that will allow computer control and data collection.

Six leads minimum (for hall bar sample measurement). You can mount samples in ceramic dip or LCC surface mount packages (up to 52 contacts), and you may find it useful to be able to measure two samples simultaneously.
Question, quotes -

please note: Each system is custom designed to the customers needs

12 CONTACTS GOLD SPRING LOADED PINS
MAXIMUM OF 52 CONTACTS
ALLOWS MULTIPLE SAMPLES PER SAMPLE CARRIER

In most cases you would like to be able to measure samples that are about 1 cm x 1 cm in area or smaller (less than 1 mm substrate thickness, and usually less than 1 um active region thickness).

SOME TYPICAL SAMPLE HOLDERS -below

Customer may chose the type of Software that they want to run under

Both Lab-View 6.1 based or MS-Visual Basic Control Software perform the following tests with respect to the change of magnet field, temperature, applied voltage, and current.

    1. Resistivity
    2. Hall Coefficient
    3. Carrier concentration and mobility
    4. Carrier type (P or N type)

The system is designed to include IEEE-488 interface that will allow computer control and data collection.

Both Software options are user modifiable.

Lab- View 6.1

LabVIEW user interface for Abbess Hall Effect Measurement System

LabVIEW was used to create the new Hall Effect Measurement System control software. The software performs the following tests with respect to changes in temperature, current, and applied voltage:
1.Resistivity
2. Hall coefficient
3. Carrier concentration and mobility
4.
Carrier type – Positive or negative semiconductors.

By varying the temperature, current, and applied voltage parameters, the user can characterize a sample at a range of magnetic fields.

The user sets the desired instrument functionality on the conditions login screen. Once completed, the software sends temperature, current, and voltage set points to a Neocera LTC temperature source, a Keithley Model 220 programmable current source, and a Keithley Model 2182 nanovoltmeter, respectively. Basic VISA and GPIB calls communicate both with SCPI devices and those that use proprietary communication standards. The main user interface is updated with the set points of each instrument
(Figure 2).
An NI 6052E data acquisition card monitors and sends digital commands to a Sorenson power supply. The system checks that each instrument has reached the target set point. When the temperature, magnet, and current are in range of their set points, the power supply creates a magnetic field and sends digital signals to a switching matrix. The switching matrix controls van der Pauw settings and calculates the resistivity of the sample under test.

The user then can vary the current, temperature, or voltage input values to do a sweep of the magnetic field, thus allowing sample characterization to be accomplished at a variety of magnetic fields. The software waits until all parameters are met and sends a series of digital outputs to the switching matrix. When the matrix has been set, the system changes the temperature, current, and magnet set points and begins again. The test is then repeated in order to get full characterization of the sample at different input values. The user can specify the number of time to repeat this testing with more repetitions causing a more accurate characterization of the sample under test. The program ends when the temperature, magnet, and current have reached their final set points as set in the conditions login screen.

Visual Basic Abbess Instruments offers an OPEN SOURCE option for system control programs. It is written in Visual Basic and runs on any PC computer running windows 95 or higher. Its first advantage over a closed source fixed universal software package is firstly that it is custom written to address the specific needs of the customer. Secondly, since the source code is available to the user it is able to be developed further as the instrument system evolves. This further development can be accomplished either by the customer alone or with assistance from Abbess Instruments. Thirdly, our open source control program integrates seamlessly with the data processing and analysis software that Abbess supplies with a full Hall Effect measurement system. Finally even with the cost of Visual Basic counted in, the open source package costs less than the closed source option.


Back to top of Abbess Main Home Page
ASTM site map
If you have any questions, need custom configurations, or a quotation,
please e-mail us at

ABBESS, INC.

Mail Address: P.O. Box 498, Ashland, MA USA 01721-0498
Shipping Address: 70 Bartzak Drive, Holliston, MA USA 01746-1158

Phone: (508) 881-8811, FAX: (508) 881-4884
Toll Free: (800) 958-8886

ABBESS IS A TRADE MARK OF ABBESS , INC, ©2006 ABBESS.

Thursday, April 09, 2009