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Applications

Hall effect measurements with ultimate precision

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Conventional Hall cross measurements are plagued by offset due to limitation of achievable cross geometry. This offset also drifts with temperature and other influences and introduces noise.

 

Zero-Offset-Hall measurements performed with Tensormeter dynamically compensate this offset, reducing offset and drift by orders of magnitude. Zero-Offset-Hall measurements provide an absolute Zero level for the Hall resistance, allowing to probe constant (invariant) Hall effects. Thus, Tensormeter opens the Nano-Ohm range for Hall effect studies.

Research faster, yet better, without lithography

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Conventionally, thin film samples are patterned in “Hall bar” or similar structures to determine resistivity, anisotropy or Hall effect. This is often done with elaborate methods like lithographic structuring.

 

By using the integrated switch matrix of the Tensormeter, the resistivity, anisotropy and Hall effect of unpatterned thin-film samples can be precisely measured. Thus, the entire lithography process for sample preparation can be skipped, which saves time and money and allows for higher sample throughput. Large material studies with many samples can be conducted without expensive lithography facilities or additional hardware.

Switched AC measurements

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Performing AC measurements has many intrinsic advantages compared to DC, like their immunity to disturbances, leading to a better base sensitivity.

Advanced measurement topologies such as Resistance Tensor measurements or Ratiometric measurements require switching contacts, which is not compatible with conventional Lock-in-amplifiers because, their demodulation lowpass filters exhibit long step responses. The unique demodulation scheme employed by the Tensormeter allows switched measurement tasks with extremely short dead time, resulting in >90% measurement time utilization when switching DUTs at 10 Hz.

Resistance Tensor measurements

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Most of research and development has treated the resistance of a material as a scalar quantity. However, it is a Tensor, which in the case of thin films is comprised of 3 physically distinct quantities: Rx, Ry, RH.

 

Each of these 3 physical quantities have different dependencies on external conditions, such as temperature or magnetic field. Each Tensor component can code different functionality in an application and all components must be studied for a comprehensive material understanding. By using the Tensormeter, the complete Resistance Tensor of a thin film can be elegantly derived by a simple 4 points measurement from the same sample.

Simultaneous DC and AC characterization

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The Tensormeter can both source and measure DC and AC signals, even simultaneously, which allows for a simultaneous measurement of DC resistance and AC impedance. It makes it possible to measure small signal resistance (dV/dI) while varying DC voltage and to measure capacitance/inductance at different bias voltage/current.

Resistor Noise Index (1/f noise) tests

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While Johnson noise is given exactly by the resistance value, the 1/f noise created by a resistor is linked to a material property called Noise Index. The precision, to which a resistor can be measured (and even defined) fundamentally depends only on its Noise Index. Thus, resistive sensors must have a low Noise Index.

The Tensormeter allows measuring extremely low Noise Indeces (<< -40 dB) within several seconds while making use of its unique operation modes such as Ratiometric AC measurements.

Ratiometric and Differential measurements

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Even the best measurement devices exhibit finite accuracy errors, some nonlinearity and drift.

 

The Tensormeter can compensate for its own errors in several important measurement schemes through the use of its switch matrix. Thus, it makes it possible to reliably measure slow ppb-level resistance changes, to measure continuously across several device ranges and to perform higher-harmonic (DUT nonlinearity) studies with ultimate sensitivity.

Van-der-Pauw measurements

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The van-der-Pauw measurement scheme allows to obtain the specific material resistivity of unpatterned thin film samples of potentially irregular shape.

While dedicated devices are available for this, all of these measurements are subsets of the capabilities of the Tensormeter and are natively supported. In addition, the Tensormeter allows for AC measurements, ratiometric tests and many other benefits.