Group‐IV Semiconductor Materials for Nanoelectronics and Cryogenic Electronics

This Special Section of physica status solidi (a) covers presentations of Symposium I held at the 2022 Fall-EMRS Meeting in Warsaw, Poland. Group-IV semiconductors, namely Si, Ge, Sn and their compounds, are the most important materials in microand nanoelectronics but they will also play a key role in future quantum devices. This symposium aimed to share the latest research in the field of group-IV nanoelectronic materials and devices. Silicon (Si) is one of the most dominant semiconductor materials with versatile applications ranging from electronics over photovoltaics to sensors and actuators. Due to their intrinsically higher electron and hole mobility germanium (Ge) or silicongermanium (SiGe) are rapidly gaining interest in microand nanoelectronics. The same holds true for tin (Sn) and its alloys with the other group-IV semiconductors (e.g., GeSn). In current nanoelectronics research with device dimensions approaching the single-digit-nanometer scale, nanowires are often the building blocks of transistors. However, many processing methods and device concepts have to be adopted since nanostructures are generically subject to nano-size and quantum effects. These effects involve for instance quantum confinement, dielectric confinement, detrimental surface states, statistical issues of doping ultrasmall volumes, etc. This bears the risk to deteriorate the performance and reliability or even cause complete failure of the transistors. On the other hand, if fully understood, nano-size and quantum effects may open up new vistas for increased performance, reduced power consumption or even routes towards quantum computing. Generally, nanostructures have a high surface-to-volume ratio and their properties are often dominated by the surface. Therefore, an increased understanding of the physical and chemical properties of group-IV semiconductor nanostructure interfaces to metals and dielectrics is mandatory to control and optimize gate control, threshold voltage, ohmic contacts, carrier transport, etc. Finally, simulations and modelling are crucial for nanoelectronics, starting from ab-initio methods to model physical/ quantum-chemical properties of group-IV nanostructures to device simulations modelling transport and performance. There are in total four research articles in this Special Section: Knoch et al. investigate by simulations and experiments the influence of the oxide-channel interfaces on the switching behavior of cryogenic field-effect transistors as well as the possibility to use a different approach than conventional doping for ultrasmall Si-nanostructures (article number 2300069). Ratschinski et al. report about another alternative silicon doping method, similar to modulation doping of III–V semiconductors, that is based on Al-doped SiO2 shells around Si nanowires (article number 2300068). The authors reveal that the electrical resistance of the nanowires is thereby reduced by several orders of magnitude. In article number 2300066, Frentzen et al. show that the electronic structure of ultrathin Si quantum wells can be shifted by embedding them in different dielectrics, i.e., SiO2 (n-type) vs. Si3N4 (p-type) behavior. Hence, this so-called NESSIAS-effect completely avoids impurity doping. Galderisi et al. study the temperature dependence of the switching behavior of reconfigurable field-effect transistors (RFET) and demonstrate how these nanoelectronics devices at extreme temperatures ranging from 80 to 475 K (article number 2300019). We thank all participants of our symposium, in particular the invited speakers, the scientific committee members, the authors of the Special Section papers, and the editors of physica status solidi (a). In addition, we appreciate the support of our symposium sponsor the European Nanoelectronics Network ASCENTþ.