Max Planck researchers from Stuttgart reveal unknown behaviour of semi-conductors at the nanoscale
Silicon is presently the most proper ingredient for microelectronic devices: it serves as basic material for all current computer chips. According to the increasing importance of electronic set-ups, the term “Silicon Age” is widely-used nowadays.
Further, the nickname Silicon Valley, representing the high-tech region in California, indi-cates the enormous importance of silicon for the semi-conductor and computer industry.
Crystalline silicon has also been widely used for the production of TFT-flatscreens and is, furthermore, a fundamental basic material for the assembling of photovoltaic cells.
A further semiconductor is germanium, which initially was the leading material in (micro) electronics, until it was replaced by silicon. Only few years ago, researchers discovered that monolayers of germanium conduct electrons up to 10 times faster than silicon. For this reason, germanium could catch up as semi-conductor again.
Silicon and germanium are both quite heat resistant and melt only at temperatures higher than 900 degree Celsius. At the solid state, the atoms are positioned within a regularly or-dered crystal lattice and can only vibrate slightly at their respective locations. With increas-ing temperature, the vibrations intensify and even “jumps“ to different sites in the solid occur. At room temperature these kind of atomic jumps are practically impossible.
Scientists led by Prof. Dr. Ir. Eric Jan Mittemeijer, Director at the Max Planck Institute for Intelligent Systems in Stuttgart, have recently discovered that atomic jumps occur in silicon and germanium even at very low temperature of minus 190 degree Celsius, if the thin layer of only 1 nanometer (millionth millimeter) gets in contact with metal, e.g. alu-minium.
The researcher Dr. Zumin Wang reports: „We tried to prepare artificial sandwiches com-posed of a very thin, 1-nm silicon or germanium film between two aluminium layers at minus 190 degree celsius. During this process we figured out that germanium or silicon always moved to the top surface of the aluminium. It was not possible to prepare such sandwiches. First, we found this “behavior” quite annoying, but soon we recognized that we had made a very surprising observation.”
While using X-ray photoelectron spectroscopy, the scientists found out that the bonding characteristics within germanium- and silicon atoms become strongly influenced when they get in touch with metals at thin-film set-ups. As a consequence, the semi-conductor atoms become able to “jump” more frequently. Because of these jumps, the atoms get mobile and change their position: they jump to the top surface of the aluminium. The metal influ-ences this mobility and has to be as close as half a nanometer.
Dr. Wang states: “This observation could become even more important since assembly parts for computers made of semi-conductor material shrink increasingly. Currently they are already as small as 10 to 40 nanometer, which means that at slightly smaller scale, mixing effects due to atomic jumps may arise. Secondly, the discovered process has impact on the preparation of thin film systems involving heat-sensitive materials, since the semi-conductor can become mobile even at very low temperature.”
Annette Stumpf | Max-Planck-Institut für Intelligente Systeme
A new tool for discovering nanoporous materials
23.05.2017 | Ecole Polytechnique Fédérale de Lausanne
Did you know that packaging is becoming intelligent through flash systems?
23.05.2017 | Heraeus Noblelight GmbH
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy