Graphene has recently attracted a great deal of interest due
to its excellent electronic transport properties and its
geoemtrical smallness that allows realizing ultimately scaled
field-effect transistors without loosing electrostatic integrity.
We fabricate buried triple- and multi-gate structures that enable
studying e.g. graphene nanoribbons, bilayer graphene
as well as alternative 2D systems in a field-effect transistor configuration.
Multilayer structures consisting of Si/SiO2 are used in 3rd generation solar cells. Quantum confinement in the Si layers is used to tune the effective band gap to the desired size enabling an absorption of UV light while minimizing relaxation losses at the same time. The transmission electron micrograph clearly shows that continuous layers of Si and SiO2 with thicknesses down to 3nm can be grown.
Tunnel FETs (TFET) with a superior switching behavior have been intensively investigated in recent years since they allow realizing energy efficient logic circuits. Optimization of the device performance is studied both experimentally as well as with simulations at our institute. The image shows the local density of states in a TFET enabling a high tunneling current to flow from source to the channel. .
The surface of solar cells is usually textured in order to suppress specular reflection of incident light yielding a significantly improved light to electricity conversion efficiency. The image shows a scanning electron micrograph of a typical texturing of a crystalline silicon solar cell.
September 27, 2013
In addition to an extension of an existing project on graphene-based band-to-band tunnel field-effect transistors, the DFG has granted the project “Strained graphene field-effect transistors – A nano-electro-mechanical transistor with MOSFET-like on currents and superior switching behavior”. The project starts at the end of 2013 and will run for the next three years.
The new project „Cantilever-field-effect transistors for the quantitative and qualitative detection of gases” aims at the realization of cantilever sensors that are based on a novel way of electronic read-out of the sensors. This novel way enables a direct integration into digital circuits without the need for an ADC. In addition, no actuator is necessary for the cantilevers strongly reducing the complexity and hence enabling the integration of a large number of cantilevers into a sensor system. The project starts in October 2013 and runs for three years.
The German ministry of education and research (BMBF) funds the new project „Ultra Low Power Electronics with Tunnel-Field-Effekt Transistors (for 0.25 Volt) “. The project targets highly energy-efficient nanoelectronics systems by combining so-called band-to-band tunnel field-effect transistors (TFETs) together with TFET sensors in dedicated circuits. TFETs have recently attracted a great deal of attention and are considered as the premier device concept for energy-autonomous/mobile applications since they potentially enable a drastic reduction of the static and dynamic power consumption of integrated circuits due to their particular switching behavior relying on the quantum mechanical tunneling process.
The project started in July 2013 and runs for three years.
May 23, 2012
In this work we report for the first time on successful direct contacting of high sheet resistance emitter at 100 Ohm/sq by emitter profile manipulation. The formation of lightly doped emitter via POCl3 diffusion was investigated and optimized by the variation of temperature, time and gas … Read More...