Composition Dependent Electrical Transport in Si<sub>1−<i>x</i></sub>Ge<sub><i>x</i></sub>Nanosheets with Monolithic Single‐Elementary Al Contacts
Lukas Wind, Masiar Sistani, Raphael Böckle, J. Smoliner, Lada Vukušić, Johannes Aberl, Moritz Brehm, Peter Schweizer, Xavier Maeder, Johann Michler, Frank Fournel, Jean‐Michel Hartmann, W. Weber
Abstract
Abstract Si 1− x Ge 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− x Ge 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− x Ge x heterostructures, obtained from a thermally induced exchange between ultra‐thin Si 1− x Ge 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− x Ge 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− x Ge 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− x Ge 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− x Ge x junctions can open up new device implementations for different types of emerging nanoelectronic, optoelectronic, and quantum devices.