Seebeck coefficient of silicon nanowire forests doped by thermal diffusion

Elyamny, Shaimaa; Dimaggio, Elisabetta; Pennelli, Giovanni

doi:10.3762/bjnano.11.153

Cited by 6 publications

(6 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[ 50 ] Contrary, the observed reduction is likely related to the suppression of the phonon drag contribution driven by the nanostructuration which doubtlessly affects the thermal conductivity. This effect is not expected to be as important as in the case of pure silicon [ 51–53 ] since germanium alloying already induces an important phonon suppression enhancement. However, it might still contribute to this reduction at the low‐temperature range.…”

Section: Resultsmentioning

confidence: 99%

“…Because at the scales of the studied NW (Φ NW ≈ 87 nm) no alteration of the electronic structure is expected -typically happening for Φ NW < 10 nm -size effects can be discarded as responsible for the observed reduced S. [50] Contrary, the observed reduction is likely related to the suppression of the phonon drag contribution driven by the nanostructuration which doubtlessly affects the thermal conductivity. This effect is not expected to be as important as in the case of pure silicon [51][52][53] since germanium alloying already induces an important phonon suppression enhancement. However, it might still contribute to this reduction at the low-temperature range.…”

Section: Thermoelectrical Propertiesmentioning

confidence: 98%

See 1 more Smart Citation

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro‐Harvesters

Gordillo

Sierra

Gadea

et al. 2023

Small

View full text Add to dashboard Cite

of trillions of delocalized sensors will require the development of robust micropower sources. [1] While primary batteries are nowadays the preferred solution, the current scenario cannot be extended much longer, as the exponentially growing number of connected devices require too complex logistics, both for their periodic replacement and disposal of such batteries. In this context, energy harvesting combined with small energy buffers (rechargeable batteries or capacitors) represents a more sustainable alternative to single-use batteries. [2][3][4] In particular, thermoelectric harvesters are solid-state devices capable of directly converting waste heat into electricity, with efficiencies in the range of 1%-10%. Among their main advantages, an absence of movable parts, high reliability, and the recently explored possibility of miniaturization make them promising candidates to power the IoT revolution. [5][6][7] The efficiency of a ThermoElectric (TE) system is measured using the so-called zT Figure of Merit, a dimensionless parameter that relates the main TE properties of the materials as zT = S 2 σT/κ, where S is the Seebeck coefficient, σ electrical conductivity, and κ its thermal conductivity. Although the thermoelectric effect is known since the 19 th century, currently, best-performing TE materials are still based on scarce, expensive, environmentally Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquidsolid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators. Thermoelectrical properties -, i.e., electrical and thermal conductivities and Seebeck coefficient -of grown nanowires are fully characterized at temperatures ranging from 300 to 600 K, allowing the complete determination of the Figure-of-merit, zT, with obtained values of 0.4 at 600 K for optimally doped nanowires. A correlation between doping level, thermoelectric performance, and elemental distribution is established employing advanced elemental mapping (synchrotron-based nano-X-ray fluorescence). Moreover, the operation of p-doped SiGe NWs integrated into silicon micromachined thermoelectrical generators is shown over standalone and series-and parallel-connected arrays. Maximum open circuit voltage of 13.8 mV and power output as high as 15.6 µW cm −2 are reached in series and parallel configurations, respectively, operating upon thermal gradients generated with hot sources at 200 °C and air flows of 1.5 m s −1 . These results pave the way for direct application of SiGe nanowire-based micro-thermoelectric generators in the field of the Internet of Things.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Thermoelectrical Propertiesmentioning

confidence: 98%

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro‐Harvesters

Gordillo

Sierra

Gadea

et al. 2023

Small

View full text Add to dashboard Cite

show abstract

“…To this end, cheap (and hence lithography-free) and reliable nanostructuring processes are needed. We developed Si-based thermoelectric generators made of large collections of vertical silicon nanowires: more than 10 7 nanowires, narrower than 80 nm and taller several hundred of micrometers, can be simultaneously fabricated by a Metal Assisted Etching process (MACE) [178][179][180], see figure 14: it consists in soaking a silicon substrate (wafer) in a diluted solution of HF and Silver Nitrate. Electrical and thermal contact can be fabricated by copper electrodeposition [179].…”

Section: Advances In Science and Technology To Meet Challengesmentioning

confidence: 99%

Roadmap on thermoelectricity

Artini

Pennelli

Graziosi³

et al. 2023

Nanotechnology

Self Cite

View full text Add to dashboard Cite

The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices.In this Roadmap an overview is given about the most recent experimental and computational results obtainedwithin the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices.

show abstract

“…The first issue is related with the doping of the nanowires, because the MACE process is reliable only on slightly doped silicon substrates [ 80 , 81 ], with doping concentrations very low with respect to those for optimal thermoelectric properties. However, a thermal diffusion doping step can be performed after the nanowire fabrication [ 82 , 83 , 84 ]. The second issue is the fabrication of contacts for the electrical and thermal transport.…”

Section: Techniques For All-silicon Thermoelectric Devicesmentioning

confidence: 99%

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

2021

Self Cite

View full text Add to dashboard Cite

The potentialities of silicon as a starting material for electronic devices are well known and largely exploited, driving the worldwide spreading of integrated circuits. When nanostructured, silicon is also an excellent material for thermoelectric applications, and hence it could give a significant contribution in the fundamental fields of energy micro-harvesting (scavenging) and macro-harvesting. On the basis of recently published experimental works, we show that the power factor of silicon is very high in a large temperature range (from room temperature up to 900 K). Combining the high power factor with the reduced thermal conductivity of monocrystalline silicon nanowires and nanostructures, we show that the foreseen figure of merit ZT could be very high, reaching values well above 1 at temperatures around 900 K. We report the best parameters to optimize the thermoelectric properties of silicon nanostructures, in terms of doping concentration and nanowire diameter. At the end, we report some technological processes and solutions for the fabrication of macroscopic thermoelectric devices, based on large numbers of silicon nanowire/nanostructures, showing some fabricated demonstrators.

show abstract

Seebeck coefficient of silicon nanowire forests doped by thermal diffusion

Cited by 6 publications

References 27 publications

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro‐Harvesters

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro‐Harvesters

Roadmap on thermoelectricity

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

Contact Info

Product

Resources

About