Dr. Klemenz’s research group focuses on the study and development of high-quality single-crystalline epitaxial films and bulk crystals for emerging technologies in various fields. The evolution towards highest-performance devices and their miniaturization require films and substrate crystals with increasing structural and surface perfection. These aspects are especially important for nano and photonic devices, where reproducibility in nanometer scale properties has to be achieved over macroscopic dimensions (3-4in).

The primary goal of this research is to achieve best device performance (and reproducibility) by improving the epitaxial deposition and bulk crystal growth processes, and by searching for new ways of synthesis. Thus, besides the growth and characterization of films and crystals by different techniques, this research includes the study of all physico-chemical, thermodynamic, and kinetic aspects involved in the crystallization and epitaxy phenomena.

Current research concerns the development of new piezoelectric (langasite-type) materials for bulk (BAW) and surface acoustic wave (SAW) devices, for example, for intermediate frequency filters for new communication systems (W-CDMA) and high-temperature sensor applications.

III-V nitrides (GaN, GaAlN, AlN) are also under investigation. High-quality films may lead to a new generation of short-wavelength blue-UV optoelectronic devices (LDs, lasers, detectors, optical data storage & communications) and high-temperature high-power electronics.

Another field of interest is high-temperature superconductivity. Due to the short coherence length in HTSCs, extremely flat film surfaces and interfaces are needed for the development of a reliable planar tunnel (JJ) device technology, for applications such as RSFQ (Rapid Single Flux Quantum) logic circuits for software define radio and ultra fast computers.

Selected Publications

C. Klemenz, M. Berkowski, B. Deveaud-Pledran, D.C. Malocha, “Defect Structure of Langasite-type Crystals: a Challenge for Applications”, Proc.2002 IEEE International Frequency Control Symposium.

C. Klemenz, “Liquid Phase Epitaxy of La3Ga5SiO14”, Proc. of 15th European Frequency and Time Forum EFTF, 2001, pp. 42-45.

C. Klemenz and H.J. Scheel, “Crystal Growth and Liquid-Phase Epitaxy of GaN”, J. Crystal Growth, Vol. 211, 2000, pp. 62-67.

C. Klemenz and H. J. Scheel, “Flat YBa2Cu3O7-x Layers for Planar Tunnel-Device Technology”, Physica C Vol. 265, 1996, pp. 126-134.

C. Klemenz, “Hollow Cores and Step Bunching Effects on (001) YBCO Surfaces Grown by Liquid-Phase Epitaxy”, J. Crystal Growth,Vol. 187, 1998, pp. 221-227.

C. Klemenz, I. Utke and H. J. Scheel, “Film Orientation, Growth Parameters and Growth Modes in Epitaxy of YBa2Cu3O7-?“, J. Crystal Growth 204 (1999) 62-68.

I. Utke, C. Klemenz, H. J. Scheel, M. Sasaura, S. Myazawa, “Misfit Problems in Epitaxy of High-Tc Superconductors”, J. Crystal Growth Vol. 174, 1997, pp. 806-812.