Doping and defects in semiconductor materials
Ion beam processing and related annealing methods are used for basic and applied studies to modify the electrical, optical and magnetic properties of semiconductor materials in a systematic manner. The work is focused on the correlation between microstructure modification on the atomic scale, i.e. the formation of clusters consisting of impurities and point defects, and the changed materials properties as well as the resulting engineering problems. Because many of the relevant processes occur during a very short time and/or in a very small volume it is often difficult to explore them experimentally. Therefore atomistic computer simulations are performed in close contact with experimental activities. Their general goal is a better understanding of ion beam- and defect-induced processes on the atomic scale.
- Doping and defect formation/annealing in Si, Ge, SiC, diamond, and ZnO with the special focus on the use of flash lamp annealing
- Formation and optimisation of Si-based light emitters (in collaboration with the research topic „Optoelectronic Materials“)
- Magnetic doping of semiconductor materials (in collaboration with the research topic „Nanoscale Magnetism“)
A key function during the experiments regarding electrical and magnetic doping as well as defect engineering plays the – unique at FZD - availability of flash lamp annealing for the time duration range 0.5-20 ms.
Also unique at FZD is an apparatus allowing simultaneous two-beam ion implantation in a synchronous mode to explore new ion beam induced effects.
Si based light emission
Rare earth (RE) elements are already successfully used in a couple of optic and optoelectronic applications like lasers, phosphors and plasma displays. They feature narrow emission lines in the ultra-violet, the visible and infrared spectral region which originate from 4f inner shell transitions.
Flash lamp annealing
Flash lamp annealing allows a fast heating up of solid surfaces with a single light flash between some hundred microseconds and some milliseconds. Thereby, the achievable final temperature of the layer could be more than 2000 oC depending on the intensity of the light flash and on the optical properties of the flash lamp annealed material. The whole equipment was developed and built in the frame work of an EU project. Now a unique apparatus is available in FZD for a well directed thermal modification of surface layers without or with reduced thermal exposure of the whole solid body
Positron annihilation spectroscopy (PAS)
Investigation of vacancy-type defects in solids and surfacesResearch topics:
- investigations of vacancy-type defects caused by ion implantation
- investigations of precipitates.
- investigations of radiation-induced damage.
- investigations of thin films and interfaces.
- methodical developments.
The program TRIDYN_HZDR simulates the dynamic change of thickness and/or composition of multicomponent targets during high-dose ion implantation or ion-beam-assisted deposition. The target and the grown layers are assumed to be amorphous. Up to 5 different atomic species, including those of the beam, may be considered.