Post Processing and Analysis with QMSA®
Lake Shore’s Quantitative Mobility Spectrum Analysis (QMSA) software package represents that most advanced multi-carrier analysis capability available. This exclusive Lake Shore software automatically segregates the mobility spectrum for each carrier species (electrons and holes) that comprise a multilayer or multi-carrier material, including heterostructures, quantum wells, and multiply doped materials. Input for the software analysis includes Hall coefficient, resistivity, and magnetic field. Output parameters include conductivity spectra as a function of mobility, number of carriers (peaks in the mobility graph), density, mobility, and sign of each carrier.
System Application Software
The fully integrated HMS software has a Windows® menu-driven interface for system operation, data acquisition, and analysis.
The menu structure and navigation functions make the platform easy to use. The software controls magnetic field, sample temperature, and sample excitation while delivering a comprehensive collection of measurement capabilities. The sample module ID feature automatically recognizes attached hardware and configures the software accordingly.
You can define and save specifications and experimental configurations as well as record and display data in laboratory and SI units for further analysis. Real-time feedback of processed data can be displayed in graphical and tabular format. With the software’s SQL reporting capabilities, data and plots can be printed or exported directly to a Microsoft Excel® spreadsheet as well as PDF or Microsoft Word® documents.
To measure sample sheet resistivity, the 8400 Series supports both van der Pauw and Hall bar measurement geometries. The Hall bar method uses one dimensional current flow approximation. You can also measure samples with gated Hall bars to account for gate bias—important for measurement of device-level material. Measure Hall density in a channel as a function of gate voltage and, as you change the gate voltage, create more or fewer carriers. The system’s program mode makes it easy to conduct gated Hall bar measurements. You can, for instance, set up a loop with varying temperatures and gate voltages and easily perform a Hall measurement using the software.
Also, through the software’s toolbox, you have complete control over the measurement parameters and can change them in real time. When combined with environmental settings like temperature, experimental parameters can be quickly determined.
Hall measurement setup
Hall measurement setup is used to define the three basic steps in a Hall measurement. These steps include checking the quality of your sample contacts, measuring the resistivity of your sample and measuring the Hall voltage.
Define a sample
Define your sample geometry and contact arrangement, as well as the maximum voltage and current applied to your sample. Sample definition parameters include thickness and sample dimensions. You can assign sample identifications and add user comments. An ASTM compliance check can also be performed.
The toolbox includes utilities that allow you to determine measurement parameters, collect and log data, and display the data on screen as a chart recorder. You have complete control over the measurement parameters and can change them in real-time. When combined with environmental settings like temperature, experimental parameters can be quickly determined.
Example of a DC measurement results screen
Example of an ohmic check