Elsevier

Vacuum

Volume 176, June 2020, 109308
Vacuum

A versatile low-cost experimental set-up and measurement protocol for temperature dependent electrical measurements in the temperature range 100 K – 500 K

https://doi.org/10.1016/j.vacuum.2020.109308Get rights and content

Highlights

  • A low-cost set-up for continuous temperature dependent electrical measurements in range 100 K – 500 K has been developed.

  • The adjoining measurement protocol has also been discussed.

  • The sample-under-test (SUT) can be either in the form of pellet or a film.

  • The heating or cooling rate of SUT in the set-up do not affect the intrinsic nature of its measured electrical properties.

  • The error in measured DC electrical resistance is ≈ ± 0.7%, which is much lower than the earlier reports.

Abstract

A versatile low-cost experimental set-up and adjoining measurement protocol for continuous temperature dependent electrical measurements in the temperature range of 100 K – 500 K is described. The set-up can perform continuous measurements of DC and AC electrical properties of a sample under test (SUT) as a function of its temperature in the mentioned temperature range without any artefacts. The SUT can be in the form of film, or, powders pressed into pellets. The set-up comprises of automatic data acquisition system equipped with LabVIEW programme for real time data acquisition during measurements. The errors involved in the measurements using the set-up have been calculated by measuring the temperature dependent resistance of standard Pt100 RTD temperature sensor and from temperature response of dielectric constant of standard polycrystalline BaTiO3. The high measurement accuracy of the present set-up in artefact-free AC and DC electrical measurements has been demonstrated by measuring the temperature response of the electrical properties of standard polycrystalline BaTiO3, standard polycrystalline SnO2 and nano polycrystalline SnO2 samples.

Introduction

Measurement of electrical properties of a material as a function of its temperature has received much interest in the recent years because of their capability to accurately determine the electrical nature of the materials pertinent to modern band theory [1]. These temperature dependent electrical measurements have proven to be very useful in specially studying the strong complex interdependence of structural disorders with polarisation and motion of charge carriers in a variety of systems ranging from Mott insulators [2], multiferroics [3], diluted magnetic semiconductors [[4], [5], [6], [7]] to polymers [[8], [9], [10]]. For example, a study of the behaviour of localised and free electrical charge carriers using temperature dependent resistivity measurements have been frequently used in determination of the dominant conduction mechanism – band to band conduction or conduction via hopping, prevalent in the material under study [[5], [6], [7]]. Similarly, temperature dependent AC measurements helps to distinguish between the localised and free band conduction in a dielectric material as well as studying the relaxor-type behaviour, and determination of the Curie point in ferroelectric materials by studying the dynamical properties such as capacitance, dielectric loss, AC conductivity, etc. [8,11,12]. At the same time, a temperature dependent electrical measurement helps to quantitatively compare the electrical response, like, DC and AC conductivity, dielectric constant, dielectric loss, etc. of different materials towards the material's temperature, which helps in realisation of efficient materials towards specific applications [13,14]. Thus, these types of measurements augment to the understanding of basic condensed matter physics as well as of technological applications.

There are various factors that are required to be cared of while performing temperature dependent DC and AC electrical measurements. Among them the crucial ones are creation of high quality vacuum environment around the sample under test (SUT), which also need to be hold on during the whole measurement; second, achieving, maintaining and reading accurate temperature of the SUT; and third, having proper arrangement for measuring the temperature dependent electrical signals of the SUT. The high quality vacuum environment around the SUT ensures that problems, such as, moisture condensation on the SUT do not happen, which otherwise can form adventitious conduction pathways on the SUT and affect the electrical measurements. Several reports are available in the literature for design of sample holders with good vacuum holding capacities in broad temperature ranges intended for measurement of various physical parameters of an SUT [[15], [16], [17], [18], [19], [20], [21]]. Experimental set-ups for continuous temperature dependent electrical measurements from much below 300 K to above are required in cases where multiple electrical transitions are present in the temperature dependent electrical spectra of an SUT, or where, it need to be cooled to ground state, which exists much below 300 K, to study its electrical properties above room temperature [3,22,23]. Many reports are available where such experimental set-ups have been discussed [17,19,20,24]. Most of these set-ups are designed for thermoelectric measurements in addition to the electrical measurement of an SUT, and make the SUT to be mounted between two metallic blocks or plates for the measurement [20,24]. Although, such arrangement is indispensable for measuring the thermoelectric properties of an SUT, but they pose some serious challenges in the measurements with high accuracy of electrical parameters, like, electrical resistance, due to a contribution from thermoelectric Seebeck and Peltier effects at the metal-SUT junctions [20]. Moreover, in such set-ups, since, the measurement of the electrical signals from the SUT are performed via the metallic blocks, such arrangements require the SUT to be tightly pressed between the blocks for good electrical contacts [20,24]. This poses some challenges, such as, the surface of the blocks should be perfectly clean and should be of correct texture so as to stay flat on the surfaces of the SUT, otherwise a gap might remain between the block and the SUT surface leading to erroneous measurements of electrical properties. Moreover, such arrangement also create difficulty for measurement with pellets of nanomaterials, since they are usually prepared at low temperatures and hence the pellets are viable to break on applying pressure. The other available set-ups, with adopted measurement procedures for dedicated measurement of electrical parameters exhibit a limited temperature applicability for these continuous temperature-dependent electrical measurements [17,19,25]. Thus, an arrangement for housing the SUT for dedicated temperature dependent electrical measurements is much required, where the contribution from such undesirable effects can be eliminated. The arrangement must allow convenient and high accuracy measurement of electrical properties of any sample. In addition, the design of such experimental set-up and the measurement protocol adopted should be such that it is simple and fully automated, so as to be of low cost, user-friendly, and can allow for highly accurate non-destructive continuous temperature dependent electrical measurements from much below room temperature to much above the room temperature.

Here, we report a simple-in-design and low-cost experimental set-up dedicated to temperature dependent DC and AC electrical measurements – DC electrical resistivity and dielectric properties, in a temperature range of 100 K – 500 K. The design of the set-up is very simple and of low-cost, such that it can be easily undertaken in a laboratory and eliminate any possible above-mentioned undesirable effects on these electrical measurements. We also develop the adjoining measurement protocol which can assist for the measurements in the above temperature range without any artefacts. The reported set-up and protocol can be coupled with proper measuring instruments designated for the intended measurements. At the end we provide measurement examples, which can estimate the instrumental errors of the set-up and also suggest its high accuracy for electrical measurements in the intended temperature range without any artefacts.

Section snippets

Details of the set-up

The set-up consists of a sample holder for mounting the sample under test (SUT), SUT being in pellet form or deposited as film on any substrate; a vacuum pump for having vacuum environment around the SUT; a cryogenic dewar for holding the sample holder and capable to lower the temperature of SUT from 300 K to 100 K; a tube furnace along-with programmable controller for holding the sample holder and capable to increase the temperature of the SUT up to at least 500 K; and measuring instruments

Measurement protocol

The present experimental set-up can be used for both the temperature dependent (DC) resistivity and temperature dependent dielectric measurements (i.e, AC measurements) of an SUT. The electrical connections to the SUT can be either in the form of 4-probe (for surface resistance measurement) or 2-probe (for bulk resistance measurement and dielectric measurement) arrangement. A schematic diagram of the SUT in 4-probe and 2-probe arrangement is shown in Fig. 6(a) and (b) respectively.

2- probe

Error analysis and measurement examples

Platinum serves as a very good material for calibration of these type of experimental set-ups. For calibrating the present set-up, a temperature (T) dependent DC resistance (RT) for a typical Pt100 resistance thermometer is shown in Fig. 7. The measurement is performed in a 4-probe arrangement. For a platinum based resistance thermometer, the resistance (RT) depends linearly on its temperature (T) as:RT=R0(1+αT)where, R0 is the resistance of the thermometer at T = 273.15 K (i.e., 0 C), and α

Summary & conclusions

A simple-in-design and low-cost experimental set-up and adjoining measurement protocol for temperature dependent DC and AC electrical measurements has been developed. The set-up is competent of doing the electrical measurements – temperature dependent resistivity and dielectric properties of a material in the temperature range of 100 K – 500 K, without any artefacts in the measured electrical spectra. The sample holder in the set-up is capable of housing a SUT either in the form of pellet or a

Declaration of competing interest

This is to declare that all authors have ‘no conflict of interest’ for this publication in Vacuum.

Acknowledgments

SR acknowledges CSIR, India for the Senior Research Fellowship vide file no. 09/013(0849)/2018 – EMR-I. AKG is thankful to DST-FIST program; to DST-PURSE program; to UGC-UPE program; to UGC-CAS program; AKG is also thankful to DAE-BRNS, India; CSIR, India; and UGC, India for financial support (Grant no. 2011/37P/11/BRNS/1038–1, 03(1302)/13/EMR-II, and F: 42–787/2013 (SR) respectively).

References (39)

  • S. Kumar et al.

    J. Phys. Chem. C

    (2012)
  • B. Prajapati et al.

    Phys. Status Solidi

    (2019)
  • R.K. Hiremath et al.

    Rev. Sci. Instrum.

    (2006)
  • X. Huang et al.

    Nanotechnology

    (2012)
  • K. Uchino

    Ferroelectrics

    (1994)
  • V. Westphal et al.

    Phys. Rev. Lett.

    (1992)
  • M. Cornils et al.

    IEEE Trans. Electron. Dev.

    (2007)
  • J.F. Scott

    Science

    (2007)
  • T. Tani et al.

    Rev. Sci. Instrum.

    (1994)
  • Cited by (1)

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