(Si,Ge,Sn)O2-based ultra-wide bandgap semiconductors for power electronics (SiGOPE)

A major challenge for a sustainable society is to ensure an economical consumption of energy. Electrical energy is a major part of today’s energy consumption and its fraction will continue to grow with increasing electro-mobility and digitalization of societies worldwide. This project aims to investigate the novel semiconductor material rutile-GeO₂ and its applications in power electronics for the development of more efficient high voltage switches. Such devices are ubiquitously used for in the electrical grid as well as electro mobility. By increasing their efficiency this project might constitute a pathway to energy saving and thus provide a significant contribution to a sustainable digital society.

While the ultrawide-bandgap semiconductor Ga₂O₃ is the currently widely-investigated top candidate for such devices (predicted to outperform even SiC and GaN), rutile-GeO₂ has recently been predicted to provide a further efficiency increase over Ga₂O₃. This performance increment is based on a higher dielectric constant, thermal conductivity, and predicted electron mobility in GeO₂ than Ga₂O₃ at similar bandgaps (E_g=4.7 eV) for both materials. Importantly, the possibility of p-type conductivity, absent in Ga₂O₃, has been predicted for rutile GeO₂ and opens up this material for bipolar devices. The related rutile oxides SnO₂ (semiconductor, E_g=3.6 eV) and SiO₂ (insulator, E_g~8 eV) bear the potential for band-gap engineering by alloying with GeO₂ for the realization of heterostructure devices (e.g., high-electron mobility field effect transistors for high-voltage and high-frequency operation) and wavelength-tunable, solar-blind UV detectors. 

In this project we want to explore the potential of the (Sn,Ge,Si)O₂ system as novel ultrawide-bandgap semiconductor with application perspectives in power electronics and UV sensing in mind, benefiting from the complementary expertise of the project partners. Starting from growth and fundamental investigations (bulk GeO₂ substrates grown at IKZ; epitaxial, doped GeO₂, (Si,Ge)O₂, and (Sn,Ge)O₂ films grown at PD)) the final goal is the realization of a GeO₂-based demonstrator power electronic device (Schottky diode or lateral field-effect transistor at FBH). TEM investigations at IKZ will clarify the microstructure and formed phases, which is particularly important for the alloy system.

Funded through the Leibniz Competition Program Collaborative Excellence in partnership with Leibniz-Institut für Kristallzüchtung (IKZ) and Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH).