No abstract

No abstract

The deposition of thin iron oxide films on Si͑100͒ by metallorganic chemical vapor deposition at 55 mbar was systematically studied as a function of temperature between 673 and 1023 K. Ferrocene and oxygen were used as precursors. The growth rate was measured as a function of temperature and the films were characterized by X-ray diffraction ͑XRD͒, Auger electron spectroscopy, energy dispersive X-ray analysis, and scanning electron microscopy. The change from the kinetically controlled regime to the transport controlled regime occurs near 750 K. At similar temperatures, a phase change of the deposited material was observed. Films prepared at temperatures higher than 823 K show the structure of ␣-Fe 2 O 3 , whereas deposition at lower temperature leads to the growth of ␣-Fe 2 O 3 and other oxide phases. The XRD pattern of these films can be explained by the coexistence of different iron oxide phases, namely ␣-Fe 2 O 3 , ␥-Fe 2 O 3 , and/or ␤-Fe 2 O 3 .

No abstract

Surface temperature measurements are crucial in many applications; one promising approach is the use of thermographic phosphors. The temperatures of surfaces coated with such a material can easily be detected by measuring and evaluating the luminescence. In the present study, the CVD of chromium-doped aluminum oxide films (ruby) on Si(100) and stainless steel substrates is investigated with respect to this application. Films are deposited in a cold-wall reactor from oxygen and the acetylacetonates of aluminum and chromium under pressures between 200 hPa (200 mbar) and 240 hPa, and at temperatures between 1273 K and 1473 K. The growth of aluminum oxide, containing 1 % chromium, is confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. While films grown at 1273 K are mainly c-Al 2 O 3 and h-Al 2 O 3 , a-Al 2 O 3 films are grown at higher temperatures. The films are analyzed by laser excitation with regard to the temperature-dependent luminescence. The films consisting of mainly a-Al 2 O 3 are promising as temperature sensors, they show the typical phosphorescence of ruby, with phosphorescence lifetimes between 2.3 ms at 298 K and 6 ls at 813 K.