@book{HirschlGriesshammerJahnetal., author = {Hirschl, Bernd and Grießhammer, Rainer and Jahn, Thomas and Hosang, Maik and Keil, Florian and Schr{\"o}der, Winfried and Walk, Heike}, title = {Climate protection demands action - Contributions Made by Social-Ecological Research}, publisher = {BMBF}, address = {Bonn [u.a.]}, pages = {40}, abstract = {Climate change impacts on the environment, people and their living conditions but also for on their possibilities for shaping their future. The Federal Government has therefore set clear and far-reaching targets for combating climate change. With its scientific technical solutions and sociological knowledge, research contributes to the implementation of these goals. Promoting and developing the carbon-free generation and use of energy as well as tapping existing potentials of energy-efficient technologies can make a decisive contribution to reducing greenhouse gas emissions. But if one looks at the challenges linked to the goal of limiting the rise in temperature to a maximum of two degrees, it is quite obvious that the problems of climate change cannot be solved through technological innovation alone. The brochure "Climate protection needs action", published by the Federal Ministry for Education and Research, shows results from research projects conducted under the support measure "socio-ecological research" which have created a solution-oriented knowledge base about the dynamic interactions between societies and their natural environment.}, language = {en} } @misc{StrobelAlvaradoChavarinVoelkeletal., author = {Strobel, Carsten and Alvarado Chavarin, Carlos and V{\"o}lkel, Sandra and Jahn, Andreas and Hiess, Andre and Knaut, Martin and Albert, Matthias and Wenger, Christian and Steinke, Olaff and Stephan, Ulf and R{\"o}hlecke, S{\"o}ren and Mikolajick, Thomas}, title = {Enhanced Electrical Properties of Optimized Vertical Graphene-Base Hot Electron Transistors}, series = {ACS Applied Electronic Materials}, volume = {5}, journal = {ACS Applied Electronic Materials}, number = {3}, issn = {2637-6113}, doi = {10.1021/acsaelm.2c01725}, pages = {1670 -- 1675}, abstract = {The arrival of high-mobility two-dimensional materials like graphene leads to the renaissance of former vertical semiconductor-metal-semiconductor (SMS) hot electron transistors. Because of the monolayer thickness of graphene, improved SMS transistors with a semimetallic graphene-base electrode are now feasible for high-frequency applications. In this study we report about a device that consists of amorphous silicon, graphene, and crystalline silicon. For the first time, this device is fabricated by a four-mask lithography process which leads to significant improvements in the device performance. A strongly increased common-emitter current gain of 2\% could be achieved while the on-off ratio improved to 1.6 × 105, which is already higher than predicted theoretically. This could be mainly attributed to better interface characteristics and decreased lateral dimensions of the devices. A cutoff frequency of approximately 26 MHz could be forecasted based on the DC measurements of the device.}, language = {en} } @misc{StrobelAlvaradoChavarinRichteretal., author = {Strobel, Carsten and Alvarado Chavarin, Carlos and Richter, Karola and Knaut, Martin and Reif, Johanna and Völkel, Sandra and Jahn, Andreas and Albert, Matthias and Wenger, Christian and Kirchner, Robert and Bartha, Johann Wolfgang and Mikolajick, Thomas}, title = {Novel Graphene Adjustable-Barrier Transistor with Ultra-High Current Gain}, series = {ACS Applied Materials \& Interfaces}, volume = {14}, journal = {ACS Applied Materials \& Interfaces}, number = {34}, issn = {1944-8244}, doi = {10.1021/acsami.2c10634}, pages = {39249 -- 39254}, abstract = {A graphene-based three terminal barristor device was proposed to overcome the low on/off ratios and insufficient current saturation of conventional graphene field effect transistors. In this study, we fabricated and analyzed a novel graphene-based transistor, which resembles the structure of the barristor but uses a different operating condition. This new device, termed graphene adjustable-barriers transistor (GABT), utilizes a semiconductor-based gate rather than a metal-insulator gate structure to modulate the device currents. The key feature of the device is the two graphene-semiconductor Schottky barriers with different heights that are controlled simultaneously by the gate voltage. Due to the asymmetry of the barriers, the drain current exceeds the gate current by several orders of magnitude. Thus, the GABT can be considered an amplifier with an alterable current gain. In this work, a silicon-graphene-germanium GABT with an ultra-high current gain (ID/IG up to 8 × 106) was fabricated, and the device functionality was demonstrated. Additionally, a capacitance model is applied to predict the theoretical device performance resulting in an on-off ratio above 106, a swing of 87 mV/dec, and a drivecurrent of about 1 × 106 A/cm2.}, language = {en} }