Planar Thermoelectric Microgenerators Based on Silicon Nanowires

Al-Dirini

et al. 2015

Sci Rep

Thermoelectric properties of Graphene nano-ribbons (GNRs) with nanopores (NPs) are explored for a range of pore dimensions in order to achieve a high performance two-dimensional nano-scale thermoelectric device. We reduce thermal conductivity of GNRs by introducing pores in them in order to enhance their thermoelectric performance. The electrical properties (Seebeck coefficient and conductivity) of the device usually degrade with pore inclusion; however, we tune the pore to its optimal dimension in order to minimize this degradation, enhancing the overall thermoelectric performance (high ZT value) of our device. We observe that the side channel width plays an important role to achieve optimal performance while the effect of pore length is less pronounced. This result is consistent with the fact that electronic conduction in GNRs is dominated along its edges. Ballistic transport regime is assumed and a semi-empirical method using Huckel basis set is used to obtain the electrical properties, while the phononic system is characterized by Tersoff empirical potential model. The proposed device structure has potential applications as a nanoscale local cooler and as a thermoelectric power generator.

“…proposed and implemented a novel thermoelectric device concept. Similarly Davila et al 4748. proposed a device concept with horizontally aligned nanowires.…”

Section: Resultsmentioning

confidence: 99%

High Performance Graphene Nano-ribbon Thermoelectric Devices by Incorporation and Dimensional Tuning of Nanopores

Al-Dirini

et al. 2015

Sci Rep

Physica Status Solidi (a)

“…The monolithic integration of silicon nanowires into microfabricated device structures was demonstrated by Dávila et al (Fig. ).…”

Section: Device Concepts For Thermoelectric Heat‐to‐electricity Convementioning

confidence: 99%

“…The trench between heat source and sink is bridged by nanowires grown by a vapor liquid solid technique in the example of Ref. .…”

Section: Device Concepts For Thermoelectric Heat‐to‐electricity Convementioning

confidence: 99%

“…Note that this device is a one‐leg thermogenerator consisting either of p‐type (as in Ref. ) or n‐type nanowires, and the thermocouple is closed by a platinum strip connecting the silicon heat sink and source. The architecture of a one‐leg device is simpler that the traditional two‐leg device architecture, and no fundamental reason objects the use of a one‐leg set‐up .…”

Section: Device Concepts For Thermoelectric Heat‐to‐electricity Convementioning

confidence: 99%

See 1 more Smart Citation

Silicon nanostructures for thermoelectric devices: A review of the current state of the art

Schierning

2014

101

Silicon is the most important element of modern semiconductor industry. As a thermoelectric converter material, it would be able to promote applications dramatically since device integration and scaling of the fabrication processes could be borrowed from existing technology. Though the thermoelectric performance of single crystalline silicon is only poor, silicon nanostructures have demonstrated a competitive figure of merit. To make use of these nanostructures, novel device architectures are necessary. This review provides an overview over the physical background of silicon as thermoelectric converter material as well as different nanostructures like nanowires, porous nanomeshes, and nanocrystalline bulk and their thermoelectric properties, focusing mostly on experimental data. Further, different thermoelectric converter device concepts including nanowire device concepts, pn junction thermoelectric generators and integrated spot coolers are discussed and their realization with silicon nanostructures briefly sketched. (a) Nanowires, porous nanomeshes and nanocrystalline bulk with promising thermoelectric material's figure of merit. (b) Innovative device concepts using nanowires or large area pn junctions for thermoelectric heat‐to‐electricity conversion.

“…9 In our previous work, the suspended platform was linked to the bulk Si rim by means of bulk Si bridges, in addition to the Si NW arrays, acting as mechanical support and as a holder for the electrical connections. [9][10][11] However, this kind of support severely reduces the platform thermal isolation due to the high thermal conductivity of the bulk Si, limiting the device ability to get a large temperature gradient from a waste heat source. Hence, long bridge supports are needed to develop large thermal gradients and significant device area is wasted giving rise to poor power densities.…”

Section: Design and Fabricationmentioning

confidence: 99%

Thermal Test of an Improved Platform for Silicon Nanowire-Based Thermoelectric Micro-generators

Calaza

Fonseca

Salleras

et al. 2015

Journal of Elec Materi

Self Cite

This work reports on an improved design intended to enhance the thermal isolation between the hot and cold parts of a silicon-based thermoelectric microgenerator. Micromachining techniques and silicon on insulator substrates are used to obtain a suspended silicon platform surrounded by a bulk silicon rim, in which arrays of bottom-up silicon nanowires are integrated later on to join both parts with a thermoelectric active material. In previous designs the platform was linked to the rim by means of bulk silicon bridges, used as mechanical support and holder for the electrical connections. Such supports severely reduce platform thermal isolation and penalise the functional area due to the need of longer supports. A new technological route is planned to obtain low thermal conductance supports, making use of a particular geometrical design and a wet bulk micromachining process to selectively remove silicon shaping a thin dielectric membrane. Thermal conductance measurements have been performed to analyse the influence of the different design parameters of the suspended platform (support type, bridge/membrane length, separation between platform and silicon rim,) on overall thermal isolation. A thermal conductance reduction from 1.82 mW/K to 1.03 mW/K, has been obtained on tested devices by changing the support type, even though its length has been halved.