Dr. Shengqiang Zhou
Head Functional Materials
Phone: +49 351 260 - 2484

Ion beam analysis for advanced materials

Key researcher: S. Zhou (s(dot)zhou(at)

Ion beam analysis ("IBA") is generally referred to a family of modern analytical techniques using MeV ion beams to probe the composition and to obtain elemental depth profiles in the near-surface region of solids. All IBA tools are highly sensitive and allow for the detection of elements in the sub-monolayer range. The depth resolution is typically in the range of a few nanometers to a few ten nanometers and recently reaches to sub-nanometer by applying high resolution detection techniques. The probed depth is from a few ten nanometers to a few ten micrometers. IBA methods are quantitative with an accuracy of a few percent and usually one does not need a standard samplefor calibration which is unavoidable for other techniques. Channeling allows to determine the depth profile of damage as well as lattice location of impurities in single crystals. In particular, Rutherford backscattering (RBS) is sensitive to heavy elements in a light matrix.  Combined with channeling, Rutherford backscattering/channeling spectrometry (RBS/C) has been used to determine the crystalline quality, the chemical concentration and the lattice distortion of semiconductor epitaxial layers.

Our activity is mainly for characterizing the semiconductor films produced by ion implantation and sub-second annealing. We can use RBS/C to check the re-crystallization process and to determine the re-distribution along depth of dopants after annealing. 

On another hand, we also use ion beam analysis as a unique method to better understand advanced materials. As one example, we apply RBS/C to directly measure the depth-profile of the tetragonal distortion in thick GaMnAs films. Even up to 2 µm, the GaMnAs film is still tetragonally strained on GaAs and there is no strain relaxation along the growth direction.


Selected Results:

 1. Depth Profile of the tetragonal distortion in GaMnAs layers


Fig (above): Illustration to explain the change of the tilt of the [112] axis in fully strained GaMnAs. For fully relaxed GaMnAs, ФR is 35.26°, while for a strained film Фs is smaller than 35.26°. By RBS channeling, Фs can be measured directly. Figure is from AIP Advances 2, 042102 (2012).


Figure (above) (a) Angular scan along the GaMnAs{110} plane, left: [001] dip and right [112] dip. A Фs of 35.19º is determined from the angular scans. (b) The depth dependence of the tetragonal distortion (eT) of the GaMnAs layer measured by RBS/channeling, indicating a uniform distribution of strain over the measured depth.  The dashed line is only a guide for eyes. There is no strain relaxation along the growth direction. Figure is from AIP Advances 2, 042102 (2012).


Figure (above) XRD RLM around 115 reflections of GaAs, LT-GaAs and GaMnAs, where reflections of all layers possess equal Qx component. This feature verifies the pseudomorphic growth of all layers in the sample and their fully strained state in respect to GaAs substrate. Figure is from AIP Advances 2, 042102 (2012).



(1) Shengqiang Zhou, Lin Chen, Artem Shalimov, Jianhua Zhao, and Manfred Helm, Depth profile of the tetragonal distortion in thick GaMnAs layers grown on GaAs by Rutherford backscattering/channeling, AIP Advances 2, 042102 (2012). (Open Access)

(2) A. N. Dobrynin, D. N. Ievlev, G. Verschoren, J. Swerts, M. J. Van Bael, K. Temst, P. Lievens, E. Piscopiello G. Van Tendeloo, S. Zhou and A. Vantomme, Atomic-scale modification of hybrid FePt cluster-assembled films, Phys. Rev. B 73, 104421 (2006).

(3) S. Zhou, A. Vantomme, B. S. Zhang, H. Yang, and M. F. Wu, Comparison of the properties of GaN grown on complex Si-based structures, Appl. Phys. Lett. 86 081912 (2005).

(4) A. N. Dobrynin, D. N. Ievlev, K. Temst, P. Lievens, J. Margueritat, J. Gonzalo, C. N. Afonso, S. Zhou and A. Vantomme, Critical size for exchange bias in a hybrid ferromagnetic-antiferromagnetic nanoparticle, Appl. Phys. Lett. 87 012501 (2005).