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Why it’s optimized for low-mobility materials

Traditional DC field Hall effect measurement is relatively straightforward and reliable for simpler materials with higher mobilities. Measurement difficulty increases and precision decreases as carrier mobilities decrease. This is often the case in promising new semiconductor materials such as photovoltaics, thermoelectrics, and organics.

AC field techniques using advanced lock-in amplifiers and longer measurement windows can extract smaller Hall voltage signals and are commonly used today to explore low mobility materials. Extended measurement intervals can also add error from thermal drift effects and results take longer to get—sometimes many hours.

The FastHall technique eliminates both of these issues — it precisely measures even extremely low–mobility materials in seconds.

low-mobility-materials

Materials

Solar cells

OPVs, a:Si, µc-Si, CdTe, CuInGaSe (CIGS)

Organic electronics

OTFTs, Pentacene, Chalcogenides, OLEDs

Transparent conducting oxides

InSnO (ITO), ZnO, GaZnO, InGaZnO (IGZO)

III-V semiconductors

InP, InSb, InAs, GaN, GaP, GaSb, AIN based devices, high electron mobility transistors (HEMTs) and heterojunction bipolar transistors

II-VI semiconductors

CdS, CdSe, ZnS, ZnSe, ZnTe, HgCdTe

Elemental semiconductors

Ge, Si on insulator devices (SOI), SiC, doped diamond SiGe based devices: HBTs and FETs

Dilute magnetic semiconductors

GaMnAs, MnZnO

Half-Heusler compounds

TiNiSn, ZrNiSn, GdPtBi

Topological semi-metals

TaAs, WTe2, MoTe2

Topological insulators

Bi2Te3, Bi2Se3, Sb2Te3

Transition-metal Di-chalcogenides (TMDC)

WS2, WSe2, MoS2, HfS2

Other 2D materials

BN, graphene structures

Other conducting materials

Metal oxides
Organic and inorganic conductors

High temperature superconductors


Measurement applications

Hall voltage

  • Resolution = 1 µV
  • Noise = 0.1 µV (RMS), averaged over 1 power line cycle

Resistance/resistivity (four-contact in-line probe and van der Pauw)

  • Calculated by instrument
  • Resistance range 10 mΩ to 1 GΩ

Magnetoresistance

  • System provides field control to measure resistance as a function of magnetic field are saved to file

Hall coefficient

  • Calculated by instrument
  • Derived from Hall voltage, magnetic field, and current

Hall mobility

  • Calculated by instrument
  • 10-2 to 106 cm2/V s

Anomalous Hall effect (AHE)

  • System provides field control to measure Hall voltage as a function of magnetic field

Carrier type/concentration/density

  • Sheet or volume carrier concentration calculated
  • Sheet carrier density ≤1017 cm-2 (carrier density depends on measurement parameters)

More science, less time

Owing to the M91 measurement controller included in the system, the FastHall Station is extremely fast, reducing analysis time in some cases by 100× when compared with various other HMS solutions. Most commonly measured materials can be analyzed in a few seconds. Even extreme high resistance (up to 1 GΩ) or low mobility (~0.01 cm²/V s) samples can generally be analyzed in under 2 min. With other HMS techniques, this could take hours to complete.

The FastHall Station encourages rapid initial assessments of materials to determine if further study or greater precision is warranted. Spend less time waiting and more time doing real science.

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Get all the data

Analysis of low mobility or high resistance materials faces challenges due to very low signal-to-noise ratios. Inaccurate measurements are likely unless sophisticated techniques and/or larger measurement samples are used. Also, with some HMS solutions, the researcher often has little chance to double check the intermediate results of the analysis, and can therefore be easily misled as to the validity of the reported results.

The FastHall Station collects all the data. In addition to performing the complete Hall analysis and outputting the usual measured and derived mobility values, the system can also generate detailed reports including all of the supporting intermediate data, so the researcher can readily confirm the integrity of the final results.

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More about the FastHall Station

FastHall Station options

Watch a hands-on demonstration video

M91/FastHall Station in research papers