Reconfigurable Field-Effect Transistor Technology via Heterogeneous Integration of SiGe with Crystalline Al Contacts
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Abstract Reconfigurable field-effect transistors, capable of being dynamically programmed during run-time, overcome the static nature of conventional complementary metal-oxide semiconductors by reducing the transistor count and the circuit path delay. Thereby, SiGe and Ge are predicted to boost drive currents, switching speed and to reduce power consumption. Nevertheless, Ge-based reconfigurable field-effect transistor prototypes have so far fallen short in reaching both the promised performance due to interface instability to their contacts and gate oxides, as well as in reaching the current?voltage symmetry necessary for circuit applicability. Here, a top-down fabricated SiGe-based reconfigurable transistor technology is reported that is comprised of a vertical Si-Si0.67Ge0.33 heterostructure enabling the envisioned high and symmetric on-currents of both n- and p-type operation. Monolithic integration with single-elementary crystalline Al contacts alleviates process variability compared to conventional Ni-silicide/Ni-germanide contacts and introduces an ultra-thin Si interlayer providing stability and equal injection efficiency of holes and electrons. The implementation of a three top-gate transistor in combination with a hysteresis-free Si/SiO2/HfO2 gate stack enhances polarity control and leakage current suppression to limit static power dissipation. Importantly, the obtained Al-Si-SiGe multi-heterojunction and advanced reconfigurable transistor design is the first Ge-based technology showing the envisioned stability and performance enhancements.