Tobias Thiede

Homoleptic Gadolinium Guanidinate: A Single Source Precursor for Metal−Organic Chemical Vapor Deposition of Gadolinium Nitride Thin Films

Deposition of a rare earth nitride thin film using a chemical gas phase deposition technique is reported for the first time. The gadolinium tris-guanidinate complex [Gd{((i)PrN)(2)CNMe(2)}(3)] is found to be an effective single source precursor for the MOCVD growth of gadolinium nitride (GdN) thin films.

All-nitrogen coordinated amidinato/imido complexes of molybdenum and tungsten: syntheses and characterization.

The first all-nitrogen coordinated bis(alkylamidinato)/bis(alkylimido) complexes of molybdenum and tungsten, [Mo(NtBu)(2){(iPrN)(2)CMe}(2)]and [W(NtBu)(2){(iPrN)(2)CMe}(2)], have been synthesized and fully characterized by (1)H and (13)C NMR spectroscopy, elemental analyses, high-resolution electron impact mass spectrometry, and Fourier transform infrared spectroscopy. Density functional theory calculations of the tungsten complex allow for geometry optimization and structural characterization by assignment of the NMR data, in particular a comparison of the experimental (13)C NMR signals with the calculated ones. Both compounds sublime without decomposition at 130 °C and 1 mTorr and show rapid decomposition above 250 °C, hence representing promising vapor-phase deposition routes for metal nitride based thin-film materials.

Evaluation of NbN thin films grown by MOCVD and plasma-enhanced ALD for gate electrode application in high-k/SiO2 gate stacks

NbN was deposited by plasma-enhanced ALD (atomic layer deposition) as well as MOCVD (metal organic chemical vapour deposition) as gate electrode for MOS capacitors with SiO2 and HfO2 as dielectric. Finally, different contact materials were deposited on the NbN electrodes and the gate stacks were annealed. Dependent on the applied dielectric and the composition of the contact materials, variation in work function, increase in EOT, and even oxide degradation occurs after thermal treatment. This can be related to chemical reactions due to interdiffusion between the NbN gate electrode, the contact material and the gate dielectric. Employing PEALD (plasma-enhanced atomic layer deposition) for NbN electrode deposition on HfO2 and poly-Si as contact material, however, degradation can be significantly reduced and the work function remains stable at 4.8 eV. This makes NbN deposited by PEALD an attractive gate electrode material for future low power consuming PMOS-transistors.

Microgradient-heaters as tools for high-throughput experimentation.

A microgradient-heater (MGH) was developed, and its feasibility as a tool for high-throughput materials science experimentation was tested. The MGH is derived from microhot plate (MHP) systems and allows combinatorial thermal processing on the micronano scale. The temperature gradient is adjustable by the substrate material. For an Au-coated MGH membrane a temperature drop from 605 to 100 °C was measured over a distance of 965 μm, resulting in an average temperature change of 0.52 K/μm. As a proof of principle, we demonstrate the feasibility of MGHs on the example of a chemical vapor deposition (CVD) process. The achieved results show discontinuous changes in surface morphology within a continuous TiO2 film. Furthermore the MGH can be used to get insights into the energetic relations of film growth processes, giving it the potential for microcalorimetry measurements.