In HZDR, a Nachwuchsgruppe, supported by Helmholtz-Gemeinschaft (the largest research association in Germany), is going to run from 2011 for five years. The research focus is “ion beam processed functional materials for spintronics and photovoltaics”. Within this theme, we are looking for Bacholar or Master (Diploma) students working on the following topics:
(1) Numerical simulation of the melting process of semiconductors under pulsed laser irradiation and of the dopant redistribution
Ion implantation plus pulsed laser annealing offer a unique, non-equilibrium approach to design highly doped semiconductors, which are key materials for semiconductor spintronics and the new generation of solar cells with a conceptual innovation. You will understand the physics of materials under pulsed laser irradiation with an extreme high power (108 W/cm2) and write code to simulate the phenomena and compare with the data published in literature.
(2) Hyperdoping Si with deep level impurities
Deep-level impurity hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of deep-level impurities (like transition metal or chalcogen) in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. However, this method encounters the problem of surface segregation. In this paper, we propose a solid phase processing by flash-lamp annealing in the millisecond range, which is in between the conventional rapid thermal annealing and pulsed laser annealing. You task is to prepare hyperdoped Si by ion implantation, to compare the annealing effect by pulsed laser and flash lamp, to characterize the structural, optical and electrical properties and to demonstrate a prototype photodetector or intermediate band solar cell.
(3) Topological insulator
Topological insulators are a new class of exciting materials with fascinating physics and a large application potential. A series of Bi2Se3 thin films have been prepared by molecular-beam epitaxy. Your task is to characterize their electrical and optical properties. This includes temperature dependent Hall measurements to determine carrier concentration and mobility, as well as optical absorption measurements by Fourier transform infrared (FTIR) spectroscopy. In addition, we would like to modify the films by ion beam doping, which will allow us to shift the Fermi energy and thus modify the properties.
You will work in an international and dynamic group with the possibility of continuing PhD study in the same group/institute. We are located in the Sachsen “Silicon Valley”, which also offer work chances in industries after this thesis training.
In the Institute of Ion Beam Physics and Materials Research at Helmholtz-Zentrum Dresden-Rossendorf, the main activities of are devoted to materials research significant for future information technology by using ion beams as an important tool for this. These activities can be grouped into six main research topics as shown in the above graphic. The research aims towards potential applications in, e.g., nanoelectronics, optoelectronics, spintronics, and photovoltaics.
The institute operates an Ion Beam Center, which is open to universities, other research institutes, and industrial partners. Additional activities are related to the free-electron laser at the superconducting electron accelerator ELBE for condensed matter research. For both facilities transnational access for external users is supported through the EU funded projects SPIRIT and ELISA, respectively. The institute also operates the materials research section of the beamline ROBL at the European Synchrotron Radiation Facility in Grenoble.