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Learn more. Volume , Issue 1. The full text of this article hosted at iucr. If you do not receive an email within 10 minutes, your email address may not be registered, and you may need to create a new Wiley Online Library account. If the address matches an existing account you will receive an email with instructions to retrieve your username. Thibault Haffner Univ. Mohammed Zeghouane Univ.
Franck Bassani Univ. Pascal Gentile Univ. Alban Gassenq Univ. Fares Chouchane Univ. Nicolas Pauc Univ. Our approach is to engineer thermoelectric materials which enhance the electrical conductivity while simultaneously blocking the tranport of thermal energy through the devices. We propose to combine the optimum 2D superlattice or 0D quantum dot material with 1D nanowire patterning to further improve the thermoelectric performance of microgenerators.
The final optimised thermoelectric generator will be integrated with a capacitor energy store on a mm-sized single silicon chip to demonstrate a power source for an autonomous system. This will be used to power a micropower CMOS sensor to demonstrate its use as an energy harvesting system.
The developed technology will be compatible with the power supply requirements for wireless autonomous systems such as those defined in the IEEE A schematic diagram showing a thermoelectric generator and the insert shows a magnified image of a single thermoelectric module using nanofabricated structures. Silicon substrates patterned by the Nanoscale Device Group using electron-beam lithography and reactive-ion etching are used as templates for the growth of Ge dots by low-energy plasma-enhanced chemical vapour deposition LEPECVD.
Current ICT is dominated by silicon because of its physically and electronically advantageous properties as well as its nearly unlimited availability. However, today's demand for ever-increasing data rates requires switching speeds beyond those which state-of-the-art electronics provide. A CMOS-compatible laser based on a group IV material is therefore extremely desirable if not mandatory to complete the monolithic integration of electronics and photonics.
Only a few years ago this idea was generally considered an engineer's dream and many scientists even discarded the idea as completely impractical. However, several very recent observations have accelerated the research in this field. Completing this technology will enable extended multi-core parallel computing with integrated lasers used for data distribution between individual cores.
Another practical advantage of the Ge material system in connection with innovative thermally induced strain and n-type doping is its emission in the 1. SiGe multiple quantum well MQW heterostructures grown by LEPECVD have demonstrated direct-gap photoluminescence at low temperature and at room temperature and above , electroluminescence at room temperature , the quantum-confined Stark effect , and transient gain. The lines represent calculations of the scattering rate based mainly on ionized dopants, with a variation in the background doping.
These mobilities are made possible in part by the high epitaxial growth rates available to LEPECVD, and also by the high quality of the virtual substrate. Relaxed graded silicon germanium buffer layers greatly extend the possibilities of the silicon germanium material system. Such a relaxed buffer layer, or virtual substrate , allows the growth of a tensile strained silicon quantum well for n -type conduction. Also, it is possible to grow compressively strained quantum wells for p -type conduction with any germanium fraction.
Fitzgerald et al. The threading dislocation density of such a buffer has been measured to be 1. Thomas et al. For comparison, the threading dislocation density of a similar buffer grown by ultra-high vacuum chemical vapour deposition UHV-CVD is 2. Samavedam et al. Such structures can have excellent electrical properties B. Low-energy plasma-enhanced chemical vapour deposition LEPECVD is a technique for growing high-quality epitaxial or nanocrystalline SiGe layers at high rates, with efficient use of the source materials. The group is equipped with a high-resolution x-ray diffractometer , which is used to measure the lattice constants of epitaxial SiGe layers and to thereby characterize their composition, strain and thickness.
The group is equipped with a Veeco Innova atomic force microscope. The microscope is used to characterize the surface morphology of as-grown SiGe layers, and to image etch pits following defect etching.
The group is equipped with a Cryogenic cryogen free i. The lowest temperature which can be reached by this cryostat is about 1. The cryostat is connected to a transport measurement system comprised of digital source meters, multi meters, preamplifiers, function generators, an oscilloscope, and an acquisition board. This system is used for the characterization of high-mobility heterostructures. Laboratory for Epitaxial Nanostructures on Silicon and Spintronics.
By making micro-bridges of germanium in which the reduction of the cross-section of the bridge at a constriction concentrates the pre-existing thermal stress left behind by the growth process, the bandgap is modified in a way which turns germanium into an efficient light emitter. SiGe islands on pit-patterned substrates Silicon substrates patterned by the Nanoscale Device Group using electron-beam lithography and reactive-ion etching are used as templates for the growth of Ge dots by low-energy plasma-enhanced chemical vapour deposition LEPECVD.
Multiple quantum wells for optical applications Current ICT is dominated by silicon because of its physically and electronically advantageous properties as well as its nearly unlimited availability. Virtual substrates Relaxed graded silicon germanium buffer layers greatly extend the possibilities of the silicon germanium material system.
X-ray diffraction The group is equipped with a high-resolution x-ray diffractometer , which is used to measure the lattice constants of epitaxial SiGe layers and to thereby characterize their composition, strain and thickness. Atomic force microscopy The group is equipped with a Veeco Innova atomic force microscope. He cryostat The group is equipped with a Cryogenic cryogen free i. Publications A. Ballabio, J. Frigerio, S. Firoozabadi, D. Chrastina, A. Beyer, K. Volz, and G. D: Appl.
Frigerio, L. Colace, and G. Isella: Design and simulation of Ge-on-Si photodetectors with electrically tunable spectral response , J. Lightwave Technol. Li, A.
Solanki, J. Frigerio, D. Chrastina, G. Isella, C. Zheng, A. Ahnood, K. Ganesan, and K. Crozier: Vertical Ge--Si nanowires with suspended graphene top contacts as dynamically tunable multispectral photodetectors , ACS Photonics 6 , Erni, F. Isa, G. Isella, H.
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