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The local heat dissipation of an in-plane gate (IPG) transistor was investigated by means of a thermally modulated scanning Joule expansion microscope. The nanostructured sample was prepared by focused ion beam techniques. The temperature induced thermal expansion and the topographic information are measured simultaneously. The spatial resolution of the constructed microscope is below 50 nm. Heat spots of the semiconducting devices are visualized by heating them with modulated drain voltage. The heat spot position and the temperature amplitude of the heat spot on the IPG transistor depend on the gate voltage VG. With an increasing negative magnitude of VG the heat spot displaces in the direction from drain towards source. Simultaneously the temperature amplitude of the maximum of the heat spot and the thermal expansion integrated over the heated area decrease linearly.

Recent advances in the development of high gauge factor thin films for strain gauges prompt the research on advanced substrate materials. A glass ceramic composite has been developed in consideration of a high coefficient of thermal expansion (9.4 ppm/K) and a low modulus of elasticity (82 GPa) for the application as support material for thin-film sensors. In the first part, constantan foil strain gauges were fabricated from this material by tape casting, pressure-assisted sintering, and subsequent lamination of the metal foil on the planar ceramic substrates. The accuracy of the assembled load cells corresponds to accuracy class C6. That qualifies the load cells for the use in automatic packaging units and confirms the applicability of the low-temperature co-fired ceramic (LTCC) substrates for fabrication of accurate strain gauges. In the second part, to facilitate the deposition of thin-film sensor structures to the LTCC substrates, pressure-assisted sintering step is modified using smooth setters instead of release tapes, which resulted in fabrication of substrates with low average surface roughness of 50 nm. Titanium thin films deposited on these substrates as test coatings exhibited low surface resistances of 850 Ω comparable to thin films on commercial alumina thin-film substrates with 920 Ω. The presented material design and advances in manufacturing technology are important to promote the development of high-performance thin-film strain gauges. *torsten.rabe@bam.de