UV and IR laser induced ablation of Al2O3/SiN:H and a-Si:H/SiN:H

Experimental work on laser induced ablation of thin Al2O3(20 nm)/SiN:H (70 nm) and a-Si:H (20 nm)/SiN:H (70 nm) stacks acting, respectively, as p-type and n-type silicon surface passivation layers is reported. Results obtained using two different laser sources are compared. The stacks are efficiently removed using a femtosecond infra-red laser (1030 nm wavelength, 300 fs pulse duration) but the underlying silicon surface is highly damaged in a ripple-like pattern. This collateral effect is almost completely avoided using a nanosecond ultra-violet laser (248 nm wavelength, 50 ns pulse duration), however a-Si:H flakes and Al2O3 lace remain after ablation process

Cotton fabrics coated with few-layer graphene as highly responsive surface heaters and integrated lightweight electronic-textile circuits

© 2020 American Chemical Society In this work, we describe an eco-friendly and cost-efficient method for the production of highly dispersed few-layer graphene solutions using karaya gum as a bioinspired exfoliating agent. The as-synthesized graphene aqueous solutions can be easily applied on a cotton cloth through dip- or brush-coating, thanks to the interaction between the graphene sheets decorated with the gum and the functional groups on the cotton cloth host substrate surface. The as-prepared fabric composites display high mechanical stability, anchorage, and high electrical conductivity that make them excellent candidates within a relatively high number of technological applications. The study mainly focuses on the potentialities of cotton fabric composites as planar heating devices or electronic-textile (e-textile) circuits prepared by postlaser treatment. By means of a laser beam, local graphitization or partial etching of the graphene conductive lines can be achieved to generate conductive areas with different resistances, which can act as flexible and integrated electronic circuits. Besides lightweight conductive circuits, the graphene-coated cotton fabrics were experimentally tested for other technological applications, that is, as flexible metal-free markers or for IR shielding or as nonflammable barriers for the protection of sensitive devices or to prevent flame spreading. This technology allows one to open a new route toward the development of daily life connected and flexible e-textile devices of added value with low carbon footprint impact

Record spintronic harvesting of thermal fluctuations using paramagnetic molecular centers

Experiments and theory are reexamining how the laws of thermodynamics are expressed in a quantum world. Most quantum thermodynamics research is performed at sub-Kelvin temperatures to prevent thermal fluctuations from smearing the quantum engine's discrete energy levels that mediate the asymmetric shuffling of electrons between the electrodes. Meanwhile, several groups report that building an electron-spin based implementation by placing the discrete spin states of paramagnetic centers between ferromagnetic electrodes can not only overcome this drawback, but also induce a net electrical power output despite an apparent thermal equilibrium. We illustrate this thermodynamics conundrum through measurements on several devices of large output power, which endures beyond room temperature. We've inserted the Co paramagnetic center in Co phthalocyanine molecules between electron spin-selecting Fe/C60 interfaces within vertical molecular nanojunctions. We observe output power as high as 450nW(24nW) at 40K(360K), which leapfrogs previous results, as well as classical spintronic energy harvesting strategies involving a thermal gradient. Our data links magnetic correlations between the fluctuating paramagnetic centers and output power. This device class also behaves as a spintronically controlled switch of current flow, and of its direction. We discuss the conceptual challenges raised by these measurements. Better understanding the phenomenon and further developing this technology could help accelerate the transition to clean energy. Abstract (150 words) Several experiments have suggested that building a quantum engine using the electron spin enables the harvesting of thermal fluctuations on paramagnetic centers even though the device is at thermal equilibrium. We illustrate this thermodynamics conundrum through measurements on several devices of large output power, which endures beyond room temperature. We've inserted the Co paramagnetic center in Co phthalocyanine molecules between electron spin-selecting Fe/C60 interfaces within vertical molecular nanojunctions. We observe output power as high as 450nW(24nW) at 40K(360K), which leapfrogs previous results, as well as classical spintronic energy harvesting strategies involving a thermal gradient. Our data links magnetic correlations between the fluctuating paramagnetic centers and output power. This device class also behaves as a spintronically controlled switch of current flow, and of its direction. We discuss th

Magnetoresistance and spintronic anisotropy induced by spin excitations along molecular spin chains

Electrically manipulating the quantum properties of nano-objects, such as atoms or molecules, is typically done using scanning tunnelling microscopes 1-7 and lateral junctions 8-13. The resulting nanotransport path is well established in these model devices. Societal applications require transposing this knowledge to nano-objects embedded within vertical solid-state junctions, which can advantageously harness spintronics 14 to address these quantum properties thanks to ferromagnetic electrodes and high-quality interfaces 15-17. The challenge here is to ascertain the device's effective, buried nanotransport path 18 , and to electrically involve these nano-objects in this path by shrinking the device area from the macro-17,19-22 to the nano-scale 23-25 while maintaining high structural/chemical quality across the heterostructure. We've developed a low-tech, resist-and solvent-free technological process that can craft nanopillar devices from entire in-situ grown heterostructures, and use it to study magnetotransport between two Fe and Co ferromagnetic electrodes across a functional magnetic CoPc molecular layer 26,27. We observe how spin-flip transport across CoPc molecular spin chains promotes a specific magnetoresistance effect, and alters the nanojunction's magnetism through spintronic anisotropy 28. In the process, we identify three magnetic units along the effective nanotransport path thanks to a macrospin model of magnetotransport. Our work elegantly connects the until now loosely associated concepts of spin-flip spectroscopy 2,3 , magnetic exchange bias 29,30 and magnetotransport 24,25 due to molecular spin chains, within a solid-state device. We notably measure a 5.9meV energy threshold for magnetic decoupling between the Fe layer's buried atoms and those in contact with the CoPc layer forming the so-called 'spinterface' 16. This provides a first insight into the experimental energetics of this promising low-power information encoding unit 31