Rolf Grieseler

Mechanical Properties of Cubic SiC, GaN and AlN Thin Films

Cubic polytypes of SiC, GaN and AlN were grown on silicon by molecular beam epitaxy. The mechanical properties of the epitaxial layers were investigated by nanoindentation. For 3C-SiC grown on Si(111) and Si(100) a dependence of the mechanical properties on the surface preparation with germanium prior to the carbonization was obtained.

Residual stress measurements and mechanical properties of AlN thin films as ultra-sensitive materials for nanoelectromechanical systems

Knowledge of the mechanical properties of new materials is essential for their usability and functionality when used in micro- and nanoelectromechanical systems (MEMS/NEMS). Recently, Group III nitrides have gained interest for MEMS and NEMS application. In order to test these materials, three different types of microstructures were fabricated by etching processes: rhombus-shaped structures and doubly-clamped beams for the determination of tensile and compressive stress as well as cantilever structures for the determination of stress gradients in the surface. Furthermore, three different methods were applied for determining the residual stress of AlN thin films: wafer bending measurements, Fourier transform infrared spectroscopic ellipsometry before the etching processes and laser Doppler vibrometer measurements after the etching processes using the doubly-clamped beams. All three methods showed a good correlation of the residual stress in the AlN thin films.

Properties of high-k materials embedded in low temperature cofired ceramics

Buried capacitors in low temperature cofired ceramics (LTCC) enable increased package density, shorter interconnects and reduced assembly time.

Effect of Post-Annealing Treatment on the Structure and Luminescence Properties of AIN:Tb3+ Thin Films Prepared by Radio Frequency Magnetron Sputtering

Terbium-doped aluminum nitride thin films have been deposited by radio frequency magnetron sputtering. The influence of annealing treatments on structural, morphological and luminescence properties of the films is examined with the aim to optimize post-deposition annealing conditions. Temperatures starting from 500 up to 1000°C using two annealing techniques were investigated: rapid thermal processing and quartz tube furnace. X-ray diffraction analysis revealed the formation of aluminum oxide and aluminum oxynitride phases at temperatures higher than 750°C. The oxygen content in the surface layer was measured with energy dispersive X-ray. The terbium emission was obtained after excitation either by photons or electrons. The films treated with rapid thermal processing at 750°C resulted in the highest emission.