We are a group of experimental physicists at the Universität des Saarlandes, specialized in nuclear solid state physics. In the focus of our interest are II-VI semiconductor compounds, where we measure defect related electric field gradients (EFG) by the perturbed angular correlation (PAC) technique and determine optical properties by photoluminescence spectroscopy. In connection with the SFB 277, we are looking at nanostructured materials using the same methods. 
We are performing experiments in Saarbrücken  and at the ISOLDE facility at CERN, Geneva. In order to complement the experimental research, we employ ab initio calculations in the framework of density functional theory (DFT) using the program package WIEN97.

PAC investigation

Incorporation and complex
formation of dopants

Identification of defects on
atomic level

Investigation of the formation of
compensating centers

Optical Methods

Identification of impurity levels in
II-VI compounds via
photoluminescence with
radioactive dopants

UV-VIS investigations

Diffusion

Analysis of diffusion of
impurities in II-VI compounds via
radiotracer technique

MOCVD growth

MOCVD growth of II-VI
compounds

In-Situ doping with the PAC
probe 111In

Hall-Measurements

Nanocrystalline semiconductors

Doping of nanocrystalline InP
with the acceptor Cd via
radioactive transmutation

Incorporation of the donor In in
nanocrystalline ZnO

Nanocrystalline metals and alloys

Investigation of grain boundery
structures by PAC-method

Microscopic inhomogenity in
nanocrystalline NiCu alloys

Impurity diffusion in nano-Ni

Ab initio DFT
Calculations

Additional information for
defects experimentally
characterised by EFG
measurement:

  - chemical nature
  - charge state
  - lattice relaxation

Theoretical analysis of the
electronic structure of
dopants and intrinsic
defects