In this paper we present the first always-delivering electrical generator (SFINKS) harvesting energy from an omnipresent energy source. This is the first harvester free of any installation constraints, and also the first micro-scale generator using atmospheric Pressure and Temperature (P/T) "tides" to produce electricity! SFINKS aims at development of quasi-eternal energy generators that can work unattended, always and everywhere. It sounds like a dream since none of the existing electricity generators is capable of doing so. Photovoltaics produce energy only when exposed to light, thermoelectric generators work only when attached to a heat source, etc. SFINKS embodies the breakthrough idea to harvest energy from natural P/T variations that are omnipresent. Therefore, SFINKS realizes the dream idea of "drop and forget " -SFINKS can be literally dropped without any care of positioning or installation. As it is inexhaustible, it can be deployed and forgotten for years, remaining operational. Solar planets and satellites can benefit from SFINKS generators, as they are subject to very large daily temperature variations.

In this paper we present the CMOS-compatible fabrication of the bi-stable silicon membrane that can be used for Energy Harvesting in micro-generator converting atmospheric pressure/temperature variations. Technological realization is industrially compatible to benefit from massive production and enable monolithic integration. The processing uses Silicon-On-Insulator technological platform and uses sequence of different layer depositions, both dielectric and metal, accompanied with wet and dry etching techniques. As a result a 1 mu m-thick various sized membranes are released. While the membrane is under-etched the internal residual stress in top silicon is released resulting in upward or downward membranes bending. Post-fabrication curvature of the membranes opens a possibility for sufficient bi-stable flexions that will be beneficial for energy production using piezoelectric materials. Atmospheric temperature/pressure variations are transformed to bi-stable membrane movements owing to liquid-to-vapour transitions of compound that fills the chamber below the membrane. This operational mode allows for harvesting energy from omnipresent daily changes of air temperature and pressure.

Always detecting, everywhere-working maintenance-free (i.e. universal) sensing devices are very important assets. In this paper, we are proposing such a universal sensing concept and present an idea of a corresponding sensor that may work 24 h a day irrespective of its location, and is capable to operate regardless of the work environment. Our innovative approach uses the Coriolis force (fictitious force due to movement in a rotational system) that acts on all moving objects and thus is almost omnipresent on Earth. The Coriolis force is generally associated with macro phenomena, such as hurricanes, water whirls, etc. In this paper the deflection of charged particles driven by the Coriolis force is studied by means of analytical calculations and numerical modelling. This deflection leads to a potential difference that is the heart of electromotive force and can thus be used for applications such as position monitoring, geographical location and maybe others to be proposed. Connecting sensors in parallel or series matrices to boost the output signal is described and studied. The output signal amplitude generated by different charged particles (electron, uranium and proton) is compared. Sensor performance is compared for different applications terrestrial, solar system planets, and for rotating machines. Numerical and analytical study confirms that this sensing idea may initiate a new type of satellite-independent position sensors.

Hg1-xCdxTe is a unique material with its bandgap being tunable by temperature, pressure, and cadmium content over a wide range, from 1.6 eV to an inverted bandgap of -0.3 eV. This makes Hg1-xCdxTe one of the key materials for infrared and terahertz detectors, whose characteristics largely depend on the material's noise properties. In this work, we investigated the low-frequency 1/f noise in a thick (800 nm) HgCdTe layer and in a field effect transistor (FET) with an 8 nm wide HgTe quantum well. Both structures exhibited a small contribution from contact noise and showed weak noise dependences on temperature. Investigation of the 1/f noise in the HgTe quantum well FET as a function of gate voltage revealed that the noise also depends weakly on electron concentration. These findings indicate that the noise properties of Hg1-xCdxTe are similar to those of graphene, where mobility fluctuations were found to be the dominant mechanism of the 1/f noise.

Hg 1-xCdxTe alloys are unique because by increasing the Cd content x, one modifies the band structure from inverted to normal, which fundamentally modifies the dispersion of bulk, surface or edge (in the case of quantum wells) energy states. Using alloys with x close to the concentration xc at which the band inversion transition is observed and with additional application of hydrostatic pressure (p), one creates a favorable playground for studying the evolution of Dirac matter and its topological properties. In this work, cryogenic magnetospectroscopy in quantizing magnetic fields (B) in the far-infrared is used to study inter-Landau-level transitions in high-quality Hg 1-xCdxTe MBE-grown epitaxial layers with x approximate to xc as a function of p up to 4.2 kbar. Special attention is paid to elucidate the role of the substrate and buffer layers, which usually modify the pressure coefficients of epitaxial layers. For this purpose, comparative measurements were carried out on as-grown epilayers with a GaAs substrate and on free-standing layers obtained by etching off the substrate. Spectra registered as a function of B (at given p) were analyzed with the help of the Kane model modified to include magnetic field. The pressure coefficient as well as the difference between conduction and valence band deformation potentials of the free-standing layer were determined at 2 K. Surprisingly, the deformation potentials and pressure coefficients of the epitaxial layer and those of the free-standing layer differed by no more than 10% in the pressure range up to 4.2 kbar. This finding questions the common belief of a dominant influence of the substrate on the pressure coefficients of epitaxial layers. We attribute the smallness of this difference to the presence of a highly disordered CdTe buffer separating the substrate from the epitaxial layer, which relaxes the transmission of strain from the substrate to the layer. Our results contribute to a better understanding of pressure experiments carried out on epitaxial layers on a substrate.

This article investigates the dichroic properties of aligned γ-Al2O3 nanofibers coated with graphene in the terahertz (THz) regime, revealing significant variance in absorption based on the orientation of the electric field in relation to the nanofibers, arising from the anisotropic nature of the material. Samples are prepared in a hot-wall chemical vapor deposition reactor with varying growth times, resulting in 5 samples with increasing graphene content. Compositional characterization is carried out using scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The samples are characterized electromagnetically using two distinct measurement techniques. First, a novel waveguide measurement setup is deployed, wherein square waveguide cassettes are used to capture the anisotropic behavior of the material and equally measure both polarization states in 67–500 GHz. Then, the samples are characterized using terahertz time-domain spectroscopy up to 4 THz. Both techniques highlight absorption enhancement when the electric field is parallel to the fibers, opening new possibilities for THz devices using polarization filtering.

Recent development of terahertz systems has created the need for new elements operating in this frequency band, i.e., fast tunable devices such as varactors. Here, we present the process flow and characterization of a novel electronic variable capacitor device that is made with the use of 2D metamaterials such as graphene (GR) or hexagonal boron nitride (h-BN). Comb-like structures are etched into a silicon/silicon nitride substrate and a metal electrode is deposited at the bottom. Next, a PMMA/GR/h-BN layer is placed on top of the sample. As voltage is applied between GR and metal, the PMMA/GR/h-BN layer bends towards the bottom electrode thus decreasing the distance between electrodes and changing the capacitance. The high tunability and complementary metal oxide semiconductor (CMOS)-compatible process flow of the platform for our device and its millimeter size make it promising for applications in future electronics and terahertz technologies. The goal of our research is to integrate our device with dielectric rod waveguides, thus making THz phase shifters.

Rapid growth is promoting the Internet of Things (IoT) to become one of the main branches of the semiconductor industry. Surprisingly, the IoT growth would have been even faster if economically attractive and reliable alternatives for batteries and wires had been available. Providing power supply to the IoT nodes is challenging regarding their: (i) quantity (close to 8x the human population), (ii) harsh operation environments, (iii) size (typical footprint much smaller than mm2) and (iv) hard-to-reach locations. Modern IoT node requires very small energy (less than 100μJ/cycle) to operate. Wire supply of energy is expensive and uncomfortable while using a battery requires periodic replacements/maintenance and produces tons of toxic waste. Energy Harvesting (EH) could be a solution to overcome the IoT supply difficulties offering self-supplied nodes enabling further IoT market growth. EH converts natural or waste energies (vibrations, heat losses, light, etc.) into useful energy. We present an innovative two-step conversion harvester capable of transforming light into electricity via the PieZoelectric (PZ) effect. Our approach uses a Photo- Mobile Polymer (PMP) integrated with the PZ material. PMP serves as light-to-movement transducer and PZ converts the light-induced PMP flexions into voltage. As a PZ material, a nanostructured ZnO nanorods were used as their fabrication is cheap and ready-to-use at industrial scale. ZnO performance characterization in a dedicated flexions simulator revealed energy as high as 80nJ during 55sec bending runs. This result encourages further PMP and ZnO optimization enabling extension of piezoelectrics onto light conversion.

None of the commonly used E nergy H arvesters ( EH ) has the quality to be an always delivering and omnipresent, i.e. an universal energy source. In this paper we are proposing such the universal energy source and present an idea of corresponding energy harvester that may harvest energy 24 hours a day irrespective of its localization. Our innovative approach uses the Coriolis force (fictitious force due to movement in a rotational system) that acts on all moving objects and thus is omnipresent on Earth (except poles). The Coriolis force is generally associated with macro phenomena like hurricanes, water whirls, etc. In this paper an unprecedented and innovative idea to use the Coriolis force to deflect charged particles is studied. This deflection leads to building up a potential difference that is heart of an electromotive force and can thus be used for energy harvesting or sensing applications.

Semiconductor industry is experiencing unprecedented growth, still driven by Moore's law, which is continually delivering devices with improved performance at lower costs. The continuation of this development places the industry in a divergent trade-off between economic attractiveness, technological feasibility, and the need for further performance improvement. Since the mainstream semiconductor technologies are silicon-based, new disruptive innovations are needed to gain additional performance margins. The use of nanowires is the preferred approach for preserving electrostatic control in the MOS transistor channel, and the application of mechanical stress is a booster of carrier mobility. It is in this context that this paper presents the design, fabrication, theoretical modeling, and characterization of a measurement platform to characterize the mechanical tensile stress of extremely narrow Si nanowires as small as 14.2 ± 1.12 nm in width. The proposed measurement platform enables a precise control of uniaxial strain, in terms of both amplitude and location, through the implementation of a stoichiometric Si3N4 pulling strand exerting a high tensile force on silicon nanowires. Reported devices are fabricated using a silicon-on-insulator wafer with fully complementary metal–oxide–semiconductor-compatible processing and top-down approach. It is observed that the mechanical strength of nanostructured Si is size-dependent and increases with miniaturization. Characterization revealed a record tensile strength value of 7.53 ± 0.8% (12.73 ± 1.35 GPa) for the narrowest nanowires fabricated using a top-down approach.

The emerging market of the Internet of Things (IoT) is gradually becoming the main driver for the entire semiconductor industry. The quantity of IoT devices already outnumbers the human population x6.5. Regarding the number, portability, and size of IoT devices, it is very challenging to provide reliable maintenance of their supply. Surprisingly, IoT devices are requiring ultra-low energy to operate, therefore, Energy Harvesting (EH) could be a fantastic solution offering energy-autonomy to IoT nodes. ThermElectricity (TE) is one the well-established EH techniques providing direct, silent, vibrationless and extremely reliable heat-to-electricity conversion. TE energy generation depends mainly on the material properties, electrical load and thermal conditions. During the conventional operation an entire ThermoElectric Generator (TEG) is quickly thermalizing that suppresses the temperature drop in steady state.Negative impact of the thermalization can be reduced when TEG is operated in pulses. Periodic connection/disconnection with the heat source allow for outstanding power boost up to x2.7 over conventional operation for same conditions. Reported pulse operation can be implemented in all types of TEGs in all temperatures. Owing to this technique, TEG can produce more energy for given temperature or can produce same energy as conventionally operated TEG from significantly lower temperatures. TEG power boost technique can help unlock further IoT expansion on the market.

Understanding how thermal-phonon paths can be shaped is key for controlling heat dissipation at the nanoscale. Thermophononic crystals are periodic porous nanostructures with thermal conductivity deviating from effective medium theory, which is possible if the characteristic sizes are of the order of phonon mean free paths and/or if phonons are forced to flow in privileged directions. We investigate suspended silicon nanomembranes with a periodic array of partially perforated holes of original paraboloid shape, with all characteristic lengths below 100 nm. Results from scanning thermal microscopy, a thermal sensing technique derived from atomic force microscopy, indicate that partial perforation of the membranes impacts heat conduction moderately, with the holey crystals showing a thermal conductivity reduction by a factor 6 in comparison to the bulk and a factor 2.5 in comparison to the non-perforated membrane. The impact of the phononic shapes is analyzed in light of a complementary Monte Carlo ray-tracing estimate of the effective phonon mean free paths that include multiple phonon reflection and highlights phonon backscattering.

The ongoing development of sub-THz systems and applications has created a need for new absorbing materials which can be integrated in a simple, low-cost manner. Here, we investigate the properties of CNT-based aerogels in the range of 67–110 GHz and develop a simple technique for their integration. The aerogels are synthesised using standard techniques and then shaped using a laser cutter to allow for direct integration. The S-parameters of a total of four aerogel absorber samples are measured. The absorbers offer a return loss of up to 12 – 14.5 dB across the measurement band, with a maximum absorption of 5 dB/mm. The observed performance makes CNT aerogels extremely promising candidates for use in sub-THz waveguide systems and applications.

Development of integrated circuits put modern microelectronics in position of constantly providing devices with better performances. This development is manifested by multiple indicators and trends including: operational frequency, (ii) miniaturization, (iii) minimization of losses, (iv) falling price, etc. In each of the aforementioned trends the microelectronics marked unprecedented progress, making the 3rd and 4th industrial revolution possible. With emerging new markets e.g. Internet of Things (loT) or Terahertz communication (THz), both operating at very high frequencies, enormous need of cheap; (ii) industrially compatible; (iii) operating at high frequencies and (iii) fully integrated devices appeared. In this context MIM (Metal Insulator Metal) diodes are gaining more and more interest. In this work we demonstrate the fabrication process flow of MIM structure acting as tunneling diodes. Presented fabrication technology is fully CMOS-compatible and consists sequence of processes including: dielectric layer deposition, metal layer sputtering, electron beam lithography, etching and metal lift-off. Subsequently after fabrication the MIM diodes were electrically characterized.

This article presents the preparation, compositional and electromagnetic characterization of modified few-walled carbon nanotubes/nanofibrillar cellulose (FWCNT/NFC) aerogels integrated in a standard terahertz hollow waveguide and studies their operation as absorbers of electromagnetic waves in the WR-3.4 band (220-330 GHz). Hybrid aerogels consisting of different weight ratios of NFC and modified FWCNT are prepared by freezedrying and characterized through scanning electron microscopy and Raman spectroscopy, and then placed within waveguide cassettes in a simple, low-cost and efficient way that requires no special equipment. A broadband measurement setup is employed for examining the electromagnetic response of the materials. It is found that the materials are excellent absorbers with an average shielding efficiency of 66 dB in the best case and return loss above 10 dB across the band with a flat frequency response. FWCNT aerogels are assessed as a promising candidate for terahertz waveguide terminations.

In this work we demonstrated the process of co-deposition of copper-tin sulfide species by the atomic layer deposition (ALD) technique using all-low-cost precursors. For the deposition of tin species, the tin(IV) chloride SnCl4was used successfully for the first time in the ALD process. Moreover, we showed that the successful deposition of the tin sulfide component was conditioned by the pre-deposition of CuSxlayer. The co-deposition of copper and tin sulfides components at 150 °C resulted in the in-process formation of the film containing Cu2SnS3, Cu3SnS4andπ-SnS phases. The process involving only tin precursor and H2S did not produce the SnSxspecies. The spectroscopic characteristic of the obtained materials were confronted with the literature survey, allowing us to discuss the methodology of the determination of ternary and quaternary sulfides purity by Raman spectroscopy. Moreover, the material characterisation with respect to the morphology (SEM), phase composition (XRD), surface chemical states (XPS), optical properties (UV-vis-NIR spectroscopy) and electric (Hall measurements) properties were provided. Finally, the obtained material was used for the formation of the p-n junction revealing the rectifyingI-Vcharacteristics.

We report on the fabrication and study of graphene gate GaN/AlGaN fin-shaped field effect transistors. The investigated DC, noise, and sub-sub-THz properties indicate their prospective for transparent high-temperature GaN-based electronics. The dependence of graphene gate properties on the bias adds new functionality to these devices.

he present experiment concerns deposition of ZnO by ALD and subsequent growth of nanowires by chemical bath. We used a novel AISI 301 steel substrate with mechanical parameters that make it suitable to use as a piezoelectric component in an energy harvesting device. We found out that a thin layer of another oxide below ZnO provides outstanding adhesion. Without it, ZnO exhibits island growth and is mechanically unstable. Such prepared samples were placed under repeated mechanical stress. They showed a piezoelectric signal which is stable after hundreds of actuations. This shows good promise for use of our device based on ZnO, an earth-abundant and non-toxic material, as an alternative to widespread in piezo components but environmentally unfriendly PZT. The piezo layers generated enough power for operations performed by a IoT chip. The designed measurement setup allowed for the demonstration of an application of AISI 301 steel substrate coated with ZnO by atomic layer and chemical bath deposition techniques as a piezoelectric component capable of generating energies usable in Internet of Things applications.

Recently, an unprecedented growth in the internet of things (IoT) is being observed, which is becoming the main driver for the entire semiconductor industry. Reliable maintenance and servicing of the IoT is becoming challenging, knowing that the IoT nodes outnumber the human population by a factor of seven. Energy harvesting (EH) can overcome those difficulties, delivering the energyautonomous IoT nodes to the market. EH converts natural or waste energies (vibrations, heat losses, air flows, light, etc.) into useful energy. This article explores the performance of ZnO nanowires under mechanical actuation to characterize their piezoelectric performance. ZnO nanowires were fabricated using ALD and a subsequent chemical bath growth. AISI 301 steel was used as a substrate of the EH device to better fit the mechanical requirements for the piezoelectric generator. We determined that a thin layer of another oxide below ZnO provides outstanding adhesion. The samples were submitted under repetitive mechanical stress in order to characterize the output piezovoltage for different conditions. They exhibited a piezoelectric signal which was stable after hundreds of actuations. This shows good promise for the use of our device based on ZnO, an Earth-abundant and non-toxic material, as an alternative to the conventional and popular but harmful and toxic PZT. The designed measurement setup demonstrated that a AISI 301 steel substrate coated with ZnO deposited by ALD and grown in a chemical bath has promising performance as a piezoelectric material. Characterized ZnO samples generate up to 80 nJ of energy during 55 s runs under matched load conditions, which is sufficient to supply a modern IoT node.