A popular approach to overcome this limitation is the course-grain reconfiguration, i.e. the signal routing to predefined logic blocks as practiced in field programmable gate arrays (FPGA). [1] This approach nevertheless leads to a high latency in data transfer and substantial chip area consumption since few active regions are not utilized at once. Distinctly, the ansatz of reconfiguration of elementary function blocks, i.e. the fine-grain reconfiguration, gives rise to a paradigm change where devices and circuits are actively redesigned after manufacturing and noteworthy even at runtime. Thereto, combinational circuits have shown benefits in area and power consumption by reconfiguration of complete logic blocks. [2] The building blocks for such circuits are RFETs, capable of merging the electrical properties of unipolar p-and n-type FETs into a single type of device with identical technology, geometry and composition. [3][4][5] Notably, RFETs do not require doping in contrast to classical FETs. Thereto, a device layout with independent gates is used to induce an additional energy barrier to the channel that blocks the undesired charge carrier type and therefore favors p-or n-type operation respectively. Consequently, reducing the technological fabrication complexity, they enable dynamic programming of circuits at the device level. [3,5] Prominent applications of such RFET devices are currently arising in the area of hardware security [6] and in highly integrated combinational and sequential logic. [5,7] Different channel materials have been employed to realize RFETs. With the use of Si channels and Ni x Si 1-x contacts various concepts with two or more independent gates have been proven experimentally. [8][9][10][11] Remarkably, symmetry in the output characteristics of p-and n-operation has been reached by the use of strain engineering both on bottom-up [12] and top-down Si nanowire RFETs [13] . Despite those outstanding efforts it has been noted, that the enhancement of the drive current and the reduction of dynamic power consumption strongly scales with the reduction of the respective Schottky barrier heights for electrons and holes. In this sense, Ge and SiGe have been identified as promising channel materials due to their reduced bandgap compared to the one of Si. Since the highest fraction of transport relevant for device and circuit performance is dictated by quantum mechanical tunneling of charge carriers [12] the use of Ge and Si x Ge 1-x channels Conventional field-effect transistor (FET) concepts are limited to static electrical functions and demand extraordinarily steep and reproducible doping concentration gradients. Reaching the physical limits of scaling, doping-free reconfigurable field-effect transistors (RFETs) capable of dynamically altering the device operation between p-or n-type, even during runtime, are emerging device concepts. In this respect, Ge has been identified as a promising channel material to enable reduction of power consumption and switching delay of RFETs. Nevertheless, its us...