Using More Germanium In Chips for Energy Efficiency & Achievable Clock Frequencies

A new technical paper titled “Composition Dependent Electrical Transport in Si_1−xGe_x Nanosheets with Monolithic Single-Elementary Al Contacts” was published by researchers at TU Wien (Vienna University of Technology), Johannes Kepler University, CEA-LETI, and Swiss Federal Laboratories for Materials Science and Technology.

Find the technical paper here. Published September 2022.

Abstract:

“Si_1−xGe_x is a key material in modern complementary metal-oxide-semiconductor and bipolar devices. However, despite considerable efforts in metal-silicide and -germanide compound material systems, reliability concerns have so far hindered the implementation of metal-Si_1−xGe_x junctions that are vital for diverse emerging “More than Moore” and quantum computing paradigms. In this respect, the systematic structural and electronic properties of Al-Si_1−xGe_x heterostructures, obtained from a thermally induced exchange between ultra-thin Si_1−xGe_x nanosheets and Al layers are reported. Remarkably, no intermetallic phases are found after the exchange process. Instead, abrupt, flat, and void-free junctions of high structural quality can be obtained. Interestingly, ultra-thin interfacial Si layers are formed between the metal and Si_1−xGe_x segments, explaining the morphologic stability. Integrated into omega-gated Schottky barrier transistors with the channel length being defined by the selective transformation of Si_1−xGe_x into single-elementary Al leads, a detailed analysis of the transport is conducted. In this respect, a report on a highly versatile platform with Si_1−xGe_x composition-dependent properties ranging from highly transparent contacts to distinct Schottky barriers is provided. Most notably, the presented abrupt, robust, and reliable metal-Si_1−xGe_x junctions can open up new device implementations for different types of emerging nanoelectronic, optoelectronic, and quantum devices.”

Citation:
Wind, L., Sistani, M., Böckle, R., Smoliner, J., Vukŭsić, L., Aberl, J., Brehm, M., Schweizer, P., Maeder, X., Michler, J., Fournel, F., Hartmann, J.-M., Weber, W. M., Composition Dependent Electrical Transport in Si1−xGex Nanosheets with Monolithic Single-Elementary Al Contacts. Small 2022, 18, 2204178. https://doi.org/10.1002/smll.202204178.

Related Reading
What’s Different About Next-Gen Transistors
Advanced etch holds key to nanosheet FETs; evolutionary path for future nodes.