Thin Film Solar Cells
Thin Film Solar cells offer a clean, low cost and efficient way of generation electric power from sunlight
At the Ångström laboratory, Uppsala University, Thin Film Solar cells based on Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSn(S,Se)4 (CZTS) are developed. The research spans from basic material and opto-electrical characterization, to process development and real, functioning devices. The devices are fabricated in dedicated equipment at the MSL.
Carbon Nanostructures For Flexible Electronics
Carbon nanotubes and graphene are 1- and 2-dimensional nanosized objects exhibiting exceptional and unique mechanical, electronic and electrical, thermal and chemical properties for a variety of emerging applications.
At UU, a research focus is placed on technology development for harnessing graphene and carbon nanotubes. The application concerns printed and flexible electronics, sensors, and thermoelectrics for energy harvesting.
Metallisation of WBG-Devices Operating at High Temperatures
Surprisingly many currently pressing societal and environmental needs require solutions where vital electronic parts must operate reliably at high temperatures and in harsh environments. The wide band gap (WBG) materials are eminently suited for this.
In collaboration with KTH-Kista, we explore novel metallisation and packaging schemes for WBG devices operating at very high temperature (up to 600 oC) in harsh environments.
3D Inter-Tier Interconnect for Future CMOS
The latest generations of microprocessors have seen stagnant performance despite continuous downscaling of CMOS. This calls for new thinking to contain power consumption, to improve performance and to enable higher-density integration.
In collaboration with KTH-Kista, we address the integration and power consumption issues by monolithically amalgamating tiers of device layers in a 3D format.
Transistor-Innovation for Single-Charge Detection
Ion sensing represents a grand research and application field. An emerging application is the recently demonstrated successful decoding of genetic information by genome sequencing using CMOS-based biochips.
We have been exploring entirely new electronic sensor device concepts towards single-charge detection. Our research spans from design and fabrication of new devices, to nanostructured surface, and to surface interaction in the electrical double layer (EDL) when operating the device in electrolytes.
Synthesis of compounds by reactive ionized sputtering
Modern society relies on novel materials with ever increasing performance. Many of such materials are used in the form of thin films.
At the Division of Solid State Electronics, we develop plasma deposition techniques suitable for low temperature synthesis of compound thin films. Our approach is based on reactive High Power Impulse Magnetron sputtering. In this technique, very high degree of ionization is achieved thanks to high instantaneous plasma densities. The ions bring significant non-thermal energy and various materials can be grown on temperature sensitive substrates.
Extremely small rockets are used for minute attitude adjustments of small spacecraft.
ÅSTC, which has worked with several aspects of microrocketry, is now looking into alternative materials permitting much higher operation temperatures in order to use the propellant more effectively than in its earlier silicon devices. Besides several rocket prototypes, flow sensors are developed with the same scheme and for the same application.
With a small and stable plasma combined with a laser, the isotope ratio of nanogram carbon samples can be determined, allowing, e.g., tracing of carbon dioxide.
ÅSTC has developed a very promising plasma source and is now integrating it with a sample handling system to form a high-temperature lab-on-a-chip device for field analysis. This includes the development of valves and sample conversion components operating at 500-1000C.
Harsh environment sensing
Monitoring processes, e.g., combustions, at around 1000C with microsensors is as interesting as it is challenging.
ÅSTC combines its expertise on high-temperature materials and devices with wireless communication to enable, e.g., reading of temperature and pressure in such extremely aggressive environments. Of immediate concern is the manufacturing of pliable elements and sealed cavities at microscale in ceramic materials.
Functional films on steel substrates
Steel substrates combine lightweight, cost reduction, mechanical resistance and may show unique assets like flexibility. But as substrates, they are not as passive as glass or silicon; what may lead to surprises while one tries to functionalize them.
Uppsala University and AC&CS CRM Group (Liege, Belgium) employ electron microscopy techniques to study thin film deposition on steel substrates. The goal of the project is to understand the reactions occurring between the thin film and the steel substrate in order to control them.
Assembly and properties of hetero-nanowire films
Semiconductor hetero-structures which can promote charge separation are interesting for applications in electronics and optoelectronics.
Chemically synthesized semiconductor hetero-wires of < 2 nm in size are fabricated as thin films employing Langmuir-Blodgett technique by ELMIN group at Uppsala University. A nanocontact platform fabricated by Lithography and Focused Ion Beam is used for the electrical characterization of the nanowire films.
Graphene defect engineering and application in environmental sensing
Graphene defect engineering means controlled defects are introduced to modify graphene structure to get the promotion of desired property. Ga ion bombardment, in-situ ion irradiation reduced functionalization and related techniques are used to change the atomic structure of graphene. In environmental gas sensing, modified graphene used in NO2 gas sensor shows 30% higher sensitivity compared with pristine graphene.
Transmission Electron Microscopy on Nanomaterials
The optical properties of metal nanoparticle embedded oxide films are determined by the size and shape of nanoparticles.
Using TEM/STEM size distributions of metal nanoparticles in TiO–2 film are determined in order to understand the relationship between the nanoparticle size and the optical properties of this nanoparticle containing thin film. The work is carried out by ELMIN group at Uppsala University
This work involves quantifying the structure of mesoporous silica media, also known as Aerogels. These materials can have a large impact on thermal insulation in the construction industry due to their low cost and weight yet high structural integrity. It is therefore critical to understand how the nanoporous structure influences their thermal conductivity.
The samples have pores on several length scales ranging from some 10nm up to micrometer sized pores. The ELMIN group approaches this question using low-energy SEM imaging, TEM, 3-D FIB imaging, electron tomography to assess the the porous nature of these complex samples.
Energy-loss Magnetic Circular Dichroism
The ELMIN group at Uppsala University develops and refines the technique of Energy-loss Magnetic Circular Dichroism (EMCD) in the Transmission Electron Microscope (TEM).
This gives us the opportunity to extract magnetic information from nanometer-sized features in ways not possible for other techniques. We can combine this with structural and chemical measurements on the same region to directly correlate these effects to magnetism, allowing for more fundamental physical questions to be addressed.
Nanoparticles embedded in matrix
Silicon nanoparticles (NPs) embedded in the insulating or semiconducting matrices has attracted much interest for the third generation of photovoltaics, “all-Si" tandem solar cells. The spatial distribution of Silicon NPs embedded in SiCx matrix in three-dimension (3D) is a critical parameter for the operation of “all-Si" tandem solar cells.
The ELMIN group at Uppsala University employs electron microscopy techniques-Electron Tomography to study the 3D distribution of Silicon NPs in SiCx matrix.
Amyloid peptides aggregations
The misfolding of protein aggregations leads to various diseases. The structural analysis on the misfolded protein aggregations provide important data to understand the driven force of protein aggregation and how the protein are expressed in different biological environments.
The ELMIN group at Uppsala University has applied Transmission Electron Microscopy (TEM) technique-Electron tomography to study the structures of Islet amyloid polypeptide (IAPP) aggregates in drosophila model.
Sustainable batteries from organic materials
Novel electrode materials for sustainable electric energy storage applications are being developed at the Ångström Laboratory.
The electrodes are based on nanocellulose fibers covered by thin layers of conducting polymers that can be further functionalized with capacity increasing red/ox units.
Upsalite® is a mesoporous magnesium carbonate material with the highest surface area ever measured for a an alkali earth metal carbonate; 800 square meters per gram.
It was invented at the Ångström Laboratory and is now being tested in moisture sorption applications as well as for delivery of poorly soluble drugs.