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Role of different scattering mechanisms on the temperature dependence of transport in graphene.

Sarkar S, Amin KR, Modak R, Singh A, Mukerjee S, Bid A - Sci Rep (2015)

Bottom Line: We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering.On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities.The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Science, Bangalore 560012, India.

ABSTRACT
Detailed experimental and theoretical studies of the temperature dependence of the effect of different scattering mechanisms on electrical transport properties of graphene devices are presented. We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering. On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities. The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms.

No MeSH data available.


Related in: MedlinePlus

Schematic of the SLG graphene device based on false colour SEM image of the device g28m6.The SLG was deposited on a 300 nm SiO2 substrate. Here RL is the ballast series resistance, Vg is the back gate voltage, and Vac is the source-drain bias, PR is the low-noise room temperature preamplifier (SR552) and LIA is the dual channel lock-in amplifier (SR830). The lower part of the image shows the distribution of the potential profile in the conducting channel due to Vg (see text for details).
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f1: Schematic of the SLG graphene device based on false colour SEM image of the device g28m6.The SLG was deposited on a 300 nm SiO2 substrate. Here RL is the ballast series resistance, Vg is the back gate voltage, and Vac is the source-drain bias, PR is the low-noise room temperature preamplifier (SR552) and LIA is the dual channel lock-in amplifier (SR830). The lower part of the image shows the distribution of the potential profile in the conducting channel due to Vg (see text for details).

Mentions: We have studied in detail the temperature dependence of the resistivity of SLG devices on SiO2 substrate to understand the temperature and gate voltage (Vg) dependencies of the scattering mechanism. SLG was exfoliated on Si/SiO2 substrate and the number of layers was confirmed using Raman spectroscopy. Electrical contacts were made on selected SLG using standard electron beam lithography techniques. Resistivity measurements were carried out on each device at low frequencies using standard 4-probe lock-in techniques. A schematic of the device is shown in Fig. 1. The measurements were all performed at low frequencies, about 228 Hz. The capacitive effect in all cases was negligible as seen from the near zero value of the quadrature component of the voltage across the sample measured simultaneously by the dual channel lock-in amplifier. The current used in these measurements was 100 nA. From the measured thermal conductivity of our graphene devices (~400 Wm−1 K−1) we estimate the maximum temperature increase of the SLG device due to Joule heating to be about 10 mK. We have carried out the measurements in multiple devices with different amounts of intrinsic disorder to quantify the effect of various types of disorder on the temperature and Vg dependencies of the resistance. In this report we present the data from a few representative devices - the details of the device parameters measured at 295 K are given in Table 1. The devices were subjected to different degrees of cleaning during the lithography process - this resulted in devices whose mobilities varied by almost than two orders of magnitude. We have quantified the amount of disorder in the different devices through the Ioffe-Regel parameter kFl, where kF is the Fermi wave-vector of the SLG and l is the carrier mean free path - the results are shown in Table 1. It can be seen that for the device with maximum disorder (g10m6) the value of kFl is very close to the Mott-Iofffe-Regel limit for metallic conduction1415.


Role of different scattering mechanisms on the temperature dependence of transport in graphene.

Sarkar S, Amin KR, Modak R, Singh A, Mukerjee S, Bid A - Sci Rep (2015)

Schematic of the SLG graphene device based on false colour SEM image of the device g28m6.The SLG was deposited on a 300 nm SiO2 substrate. Here RL is the ballast series resistance, Vg is the back gate voltage, and Vac is the source-drain bias, PR is the low-noise room temperature preamplifier (SR552) and LIA is the dual channel lock-in amplifier (SR830). The lower part of the image shows the distribution of the potential profile in the conducting channel due to Vg (see text for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660441&req=5

f1: Schematic of the SLG graphene device based on false colour SEM image of the device g28m6.The SLG was deposited on a 300 nm SiO2 substrate. Here RL is the ballast series resistance, Vg is the back gate voltage, and Vac is the source-drain bias, PR is the low-noise room temperature preamplifier (SR552) and LIA is the dual channel lock-in amplifier (SR830). The lower part of the image shows the distribution of the potential profile in the conducting channel due to Vg (see text for details).
Mentions: We have studied in detail the temperature dependence of the resistivity of SLG devices on SiO2 substrate to understand the temperature and gate voltage (Vg) dependencies of the scattering mechanism. SLG was exfoliated on Si/SiO2 substrate and the number of layers was confirmed using Raman spectroscopy. Electrical contacts were made on selected SLG using standard electron beam lithography techniques. Resistivity measurements were carried out on each device at low frequencies using standard 4-probe lock-in techniques. A schematic of the device is shown in Fig. 1. The measurements were all performed at low frequencies, about 228 Hz. The capacitive effect in all cases was negligible as seen from the near zero value of the quadrature component of the voltage across the sample measured simultaneously by the dual channel lock-in amplifier. The current used in these measurements was 100 nA. From the measured thermal conductivity of our graphene devices (~400 Wm−1 K−1) we estimate the maximum temperature increase of the SLG device due to Joule heating to be about 10 mK. We have carried out the measurements in multiple devices with different amounts of intrinsic disorder to quantify the effect of various types of disorder on the temperature and Vg dependencies of the resistance. In this report we present the data from a few representative devices - the details of the device parameters measured at 295 K are given in Table 1. The devices were subjected to different degrees of cleaning during the lithography process - this resulted in devices whose mobilities varied by almost than two orders of magnitude. We have quantified the amount of disorder in the different devices through the Ioffe-Regel parameter kFl, where kF is the Fermi wave-vector of the SLG and l is the carrier mean free path - the results are shown in Table 1. It can be seen that for the device with maximum disorder (g10m6) the value of kFl is very close to the Mott-Iofffe-Regel limit for metallic conduction1415.

Bottom Line: We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering.On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities.The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Science, Bangalore 560012, India.

ABSTRACT
Detailed experimental and theoretical studies of the temperature dependence of the effect of different scattering mechanisms on electrical transport properties of graphene devices are presented. We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering. On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities. The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms.

No MeSH data available.


Related in: MedlinePlus