We are continuously looking for Bacholar or Master (Diploma) students. If you are interested in working in our group, please contact the responsible persons.
- Hyperdoped Si by deep level impurities
The hyperdoping of semiconductors consists of introducing dopant concentrations far above the solubility limits. This can be achieved by ion implantation and pulsed laser melting. Hyperdoing leads to a broadening of dopant energy level into an impurity or intermediate band. We have recently demonstrated that hyperdoping Si with Se or Te shows promise for Si-based short-wavelength infrared photodetectors [Y. Berencén, et al., “Room-temperature short-wavelength infrared Si photodetector” Sci. Rep. 7, 43688 (2017) and M. Wang et al., "Extended Infrared Photoresponse in Te-Hyperdoped Si at Room Temperature" Physical Review Applied 10, 024054 (2018) ]. The hyperdoped semiconductors are meta-stable materials and may undergo deactivation upon thermal processing even at low temperature. Your task is to investigate the effect of rapid thermal annealing on hyperdoped Si. You will measure the structural, electrical and optical properties and find their correlation.
Contact: Mao Wang (m.wang(at)hzdr.de) and Dr. Shengqiang Zhou (s.zhou(at)hzdr.de).
- Single color centers in silicon
Silicon nanophotonics has become one of the most promising photonic-electronic integrated platforms triggered by high demand in the realm of information technology to increase communication and computation bandwidth. This is mostly due to the very high refractive index contrast of Si with Si-based compounds and the maturity level of the existing complementary metal–oxide–semiconductor (CMOS) technology, which enables the fabrication of photonic integrated circuitry in a highly economic way. Waveguides and photodetectors have successfully been integrated in a Si photonic chip. However, the main difficulty nowadays in obtaining a fully photonic integrated circuitry lies in the development of an efficient light source, since the indirect nature of the Si band gap hinders efficient light emission for such a purpose. Your work will be devoted to create, in a controllable manner, single color centers in silicon by ion beam irradiation with nanometer-scale precision and their further integration into high-quality photonic cavities to achieve an efficient single-photon source.
Contact: Dr. Yonder Berencen (y.berencen(at)hzdr.de) and Dr. Georgy Astakhov (g.astakhov(at)hzdr.de).
- Superconducting Ge for quantum technology
Since the discovery of superconductivity in diamond [E. A. Ekimov, et al., Nature 428, 542 (2004)] with boron content above the equilibrium solid solubility many studies have been performed to find new “superconducting semiconductors”. Such a materials class would enable the monolithic integration of quantum and conventional electronics. Indeed, several groups found superconductivity even in the technological more relevant semiconductors like Si [E. Bustarret, et al. Nature 444, 465 (2006)], Ge [T. Herrmannsdörfer, et al., Phys. Rev. Lett. 102, 217003 (2009)] and SiC [T. Muranaka, et al., Sci. Technol. Adv. Mater., 9, 044204 (2008)] after heavy hole doping. It is an unresolved question whether superconducting semiconductor films and nanowires can be fabricated at all by todays’ top down selective doping technologies and which semiconductor-acceptor combination is most promising. Your task is to prepare superconducting, single crystalline Ge (film and nanowire) by ion implantation. You will measure the electrical and structure properties of the fabricated materials.
Contact: Dr. Slawomir Prucnal (s.prucnal(at)hzdr.de) and Dr. Shengqiang Zhou (s.zhou(at)hzdr.de).