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AALTO

AALTO-KORKEAKOULUSAATIO
Country: Finland
414 Projects, page 1 of 83
  • Open Access mandate for Publications
    Funder: EC Project Code: 825142
    Overall Budget: 150,000 EURFunder Contribution: 150,000 EUR
    Partners: AALTO

    Joule heating due to electrical resistance associated with current spreading in semiconductors is a significant loss mechanism in modern state-of-the-art high power light emitting diodes (LEDs) and high concentration solar cells. These losses can account for up to 10-30 % of the device power consumption under high power conditions, and thereby dramatically reduce the efficiency of solar energy harvesting and general lighting, whose efficiencies – apart from the resistive losses – are gradually closing in on their theoretical limits. In ZeroR we make use of a conceptually simple but functionally dramatic modification to the previous buried active region (AR) devices, like LEDs, lasers and solar cells, by relocating the AR to outside the pn-junction, allowing e.g. locating the AR on the device surface – or locating all the contact structures fully on one side of the active region, eventually enabling a fully scalable and essentially resistance free structures. We analyze the commercial prospects of the technology and show that it provides new freedom for high power semiconductor device design. The main goal of ZeroR is to facilitate further commercial development of the concept and to demonstrate the elimination of resistive losses in industrially relevant LED and solar cell prototypes using gallium nitride and gallium arsenide based compound semiconductor material systems. If successful, this approach can substantially increase the device efficiency at selected high power operating conditions and substantially expedite the ongoing solid state lighting revolution and market penetration, also providing more efficient new solutions for solar energy harvesting and selected other applications.

  • Open Access mandate for Publications and Research data
    Funder: EC Project Code: 803937
    Overall Budget: 1,499,940 EURFunder Contribution: 1,499,940 EUR
    Partners: AALTO

    Active particles refer to out-of-equilibrium self-propulsive objects such as biological microswimmers and engineered colloidal particles that can form various fascinating collective states. Active particles are easy to observe experimentally but notoriously difficult to interact with due to their fast and stochastic dynamics at both single-particle and collective state levels. In this project, I aim at scientific breakthrough in both instrumentation that allows direct interaction with active particles and using the methodology to progress substantially our understanding of dynamics and phase transitions of active particles. The first part focuses on rendering active particles, including E. coli, C. reinhardtii and Quincke rollers, permanently magnetized and designing suitable hardware for controlling them in real time. These particles are rendered “intelligent” by programming their behavior based on real-time image analysis (long-range vision) and steering with external magnetic field. I will program these particles to reveal the limits of using local dissipative hydrodynamic near-fields to guiding active particles, and demonstrate unambiguously the extent to which a single active particle within a collective state can control the collective behaviour. The second part aims at realizing tuneable magnetic traps and other conservative potential energy landscapes for non-magnetic active particles by using magnetophoresis in superparamagnetic fluids. I will use the technique to establishing confinement-activity phase diagrams for both biological (C. reinhardtii) and synthetic (Quincke rollers) active particles in quadratic confinements. I will further reveal the role of dimensionality (1D vs 2D vs 3D) in the phase transitions of active particles and carry out the seminal investigation of active particles in periodic potentials. The results and methodologies will have a major impact, both immediately and in long-term, on experimental physics of active particles.

  • Open Access mandate for Publications
    Funder: EC Project Code: 834742
    Overall Budget: 2,442,450 EURFunder Contribution: 2,442,450 EUR
    Partners: AALTO

    The project aims at introducing a paradigm shift in the development of nonlinear photonics with atomically-engineered two-dimensional (2D) van der Waals superlattices (2DSs). Monolayer 2D materials have large optical nonlinear susceptibilities, a few orders of magnitude larger than typical traditional bulk materials. However, nonlinear frequency conversion efficiency of monolayer 2D materials is typically weak mainly due to their extremely short interaction length (~atomic scale) and relatively large absorption coefficient (e.g.,>5×10^7 m^-1 in the visible range for graphene and MoS2 after thickness normalization). In this context, I will construct atomically-engineered heterojunctions based 2DSs to significantly enhance the nonlinear optical responses of 2D materials by coherently increasing light-matter interaction length and efficiently creating fundamentally new physical properties (e.g., reducing optical loss and increasing nonlinear susceptibilities). The concrete project objectives are to theoretically calculate, experimentally fabricate and study optical nonlinearities of 2DSs for next-generation nonlinear photonics at the nanoscale. More specifically, I will use 2DSs as new building blocks to develop three of the most disruptive nonlinear photonic devices: (1) on-chip optical parametric generation sources; (2) broadband Terahertz sources; (3) high-purity photon-pair emitters. These devices will lead to a breakthrough technology to enable highly-integrated, high-efficient and wideband lab-on-chip photonic systems with unprecedented performance in system size, power consumption, flexibility and reliability, ideally fitting numerous growing and emerging applications, e.g. metrology, portable sensing/imaging, and quantum-communications. Based on my proven track record and my pioneering work on 2D materials based photonics and optoelectronics, I believe I will accomplish this ambitious frontier research program with a strong interdisciplinary nature.

  • Open Access mandate for Publications and Research data
    Funder: EC Project Code: 892856
    Overall Budget: 202,681 EURFunder Contribution: 202,681 EUR
    Partners: AALTO

    In researches about hydrogen oxidation reaction (HOR) at the anode of a fuel cell, most researchers concentrate on the intrinsic activity and stability of catalysts, while few researches study the gas diffusion effect in depth, which is however the rate-determine step for most HOR. Enlightened by the efficient lungs’ supply of oxygen to human with multistage bronchi and pulmonary alveoli, we plan to improve the hydrogen gas diffusion for HOR by constructing multistage superaerophilic gas channels (MSGC) in the catalyst layer (CL). Traditionally, to build gas channels in CL, people modify powder catalysts with aerophilic binder, which however cause aggregation and therefore hindered the transfer of electron and mass. Besides, part of the randomly made gas channels are closed that cannot transfer hydrogen actually. Thus, there are two challenges in MSGC construction: a solid and strong hierarchical micro-nano skeleton, that won’t aggregate, to support catalyst and channels, and a method to control the direction of the channels. Herein, we propose tungsten carbide nanoarrays (WC NA) as the skeleton for Pt catalyst and invent a vacuum-control method based on superwetting technology to direct the gas channels. Although WC nanoparticles have been proved promising as the substrate of Pt for HOR, WC NA has never been tried. Based on the novel structure, we will study the relationship between structure, gas diffusion, and HOR efficiency in depth. Targeting at the rate-determine step of HOR, we’re expecting a theoretical breakthrough in HOR, which will offer an alternative approach for making hydrogen anode in fuel cell industry.

  • Open Access mandate for Publications and Research data
    Funder: EC Project Code: 705222
    Overall Budget: 191,326 EURFunder Contribution: 191,326 EUR
    Partners: AALTO

    Sandwiching ultra-thin out-of-plane magnetized materials between heavy metal and oxide layers in multilayer heterostructures has led to important new discoveries which offer a path to fast, non-volatile, low power electronics. The first important effect, the Dzyaloshinskii-Moriya interaction (DMI), favours orthogonal alignment of neighbouring spins, causing stable Néel domain walls of well-defined chirality. The second, spin-orbit torques (SOTs), are torques on the magnetization caused by spin accumulation under applied in-plane currents. In combination these effects lead to very high domain wall velocities and allow the creation of mobile topological objects called skyrmions, both suitable for technological applications. While DMI and SOTs are dominated by the interfaces, their precise microscopic origins are not well understood. This proposal takes advantage of newly developed techniques to control magnetic interfaces with electric fields. Through strain effects, created by electric fields on a ferroelectric layer, or through electrical fields across an insulating oxide or through electric field-induced oxygen migration in an ionic conductor, the interfacial properties of suitable devices will be altered. All these effects change the filling of hybridized interfacial electronic orbitals, which allows the strength of the DMI and SOTs to be tuned for applications and lead to a better understanding of the underlying mechanisms. Magintlec will be conducted at Aalto University where the host group provides frontier expertise and state-of-the-art experimental facilities for electric-field controlled magnetism (film growth, lithography, magnetic and magnetotransport characterization). The applicant, Dr Rhodri Mansell, brings an excellent track record in nanomagnetism and spintronics. For the last five years, he worked as a postdoctoral research associate at Cambridge University focusing on spin-orbit effects and logic devices in out-of-plane magnetized multilayers.