Theoretical investigation of effect of pore size and pore passivation on the thermoelectric performance of silicene nano
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Deep Kamal Kaur Randhawa Department of Electronics and Communication Engineering, Guru Nanak Dev University, Ladhewali 144007, Punjab, India
Sukhleen Bindra Naranga) Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005, Punjab, India (Received 11 April 2017; accepted 18 July 2017)
Persistent evolution and scaling down of integrating circuits have created a need to identify new thermoelectric materials that can be exploited to convert dissipated heat into electrical energy. We demonstrate that thermoelectric performance of silicene nanoribbons (SiNRs) can be enhanced by introducing nanopores We observe that with the incorporation of pores, thermal conductance of SiNRs is reduced which in turn leads to enhancement of thermoelectric performance (high ZT). Although the Seebeck coefficient degrades in the presence of pore, the conductivity exhibits an improved pattern, in effect contributing to better performance. In this paper, our aim is to tune the pore to its optimal dimension so as to enhance the overall thermoelectric efficiency and to study the effect of passivation at the pore edges on the thermoelectric parameters. It is further analyzed that with the pore passivation, the thermal conductance exhibits a width-dependent oscillating behavior. Ballistic transport regime and semi-empirical method using Huckel basis set are used to obtain the electrical properties, while the Tersoff potential is used for the phononic system.
I. INTRODUCTION
Silicene is a two-dimensional (2D) one-atom-thick crystalline form of silicon, one of the most abundantly and widely used materials in the electronics industry.1 Silicene is being studied with an effort to understand its thermoelectric properties and enhance the thermoelectric performance with an intention of designing silicon compatible electronic devices to utilize thermoelectric energy. Silicon in bulk has high thermal conductance which is less desirable for thermoelectric conversion. One promising route is to take advantage of reduced phonon thermal conductance in low dimensional materials which can be obtained by nanostructuring it to create nanoribbons.1–5 Thermal conductance reduction could be further engineered in porous silicene nanoribbons (SiNRs) since phonon thermal conductance is reduced in nanoporous semiconductors.1,6,7 Additionally, its slightly buckled structure8–15 opens up the possibility of a tunable bandgap16 which is essential for a better value of Seebeck coefficient. The efficiency of a thermoelectric material is evaluated by the dimensionless figure of merit ZT which is expressed as ZT 5 S2GT/k, where S is the Contributing Editor: Terry M. Tritt a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.326
Seebeck coefficient, G is electrical conductance, T is temperature, and k is thermal conductance. Here, k is the summation of electron thermal conductance ke and phonon thermal conductance kph. The quantity S2G is called the power factor (PF) which is a measure of output voltage and curren
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