Freudenblum, D.; Gruber, G.; Schwiddessen, R.; Ruske, F.; Weinberger, N.: In-situ temperature calibration for high temperature XRD experiments in vacuum demonstrated on pristine and Nb doped TiO2-x thin films. Journal of Alloys and Compounds 1036 (2025), p. 181844/1-11
10.1016/j.jallcom.2025.181844
Open Access Version
Abstract:
We present an in-situ temperature calibration technique for high temperature grazing incident X-ray diffraction experiments conducted in high-vacuum. Thermal lattice extension of a crystalline platinum thin film is used to calibrate the temperature in the sample to the control-temperature measured by a thermocouple. This enables a precise thermal analysis of thin film crystal structures with an uncertainty of less than 10 K. Using this technique, we examine the crystallization behavior of pristine and niobium-doped titanium dioxide thin films, deposited by direct current magnetron sputtering from metal–ceramic composite targets. Crystallization onset temperatures and structural evolution were assessed for various target compositions and process conditions, revealing that increased metal content in the composite target tends to promote rutile phase formation during vacuum annealing. For the target containing 10wt% niobium – identified as the most promising for a transparent conductive oxide application – an oxygen flow variation is evaluated. Results reveal significant differences in the crystal lattice depending on the oxygen flow during deposition. Introducing 0.2 % oxygen to the argon process gas is sufficient to induce the formation of pure anatase phase during heat treatment, yielding a minimum resistivity of 1.2 m Ω cm. Our findings highlight the crucial role of oxygen content in tailoring both the structural and opto-electrical properties of titanium dioxide based thin films, providing essential insights for the definition of optimal process windows.