(I) Early Alterations of Apoptosis and Cell Proliferation in Azoxymethane-initiated Rat Colonic Epithelium (II) Expression of Bcl-2, Bax and Bcl-XL proteins in the azoxymethane-induced rat colonic adenocarcinomas

(I) Early Alterations of Apoptosis and Cell Proliferation in Azoxymethane-initiated Rat Colonic Epithelium(II) Expression of Bcl-2, Bax and Bcl-XL proteins in the azoxymethane-induced rat colonic adenocarcinoma

Ferroelectric, Pyroelectric and Piezoelectric Effects of Hafnia and Zirconia Based Thin Films

Ferroelectric materials are of great interest for several applications. On the one hand, theferroelectric field effect transistor (FeFET) is a promising candidate for future high density, nonvolatile memory devices. On the other hand, in the recent years the energy related applications such as pyroelectric and piezoelectric energy harvesting as well as electrocaloriccooling and electrostatic energy storage attracted wide interest. The conventional ferroelectricmaterials such as lead zirconatetitanate (PZT) are not completely CMOS compatible and therefore a high-density integration for memory application could not be realized up to date.Furthermore, PZT has environmental issues due to the contained lead.Ferroelectric hafnium oxide, which was first reported in 2011, can overcome the mentioneddrawbacks of the conventional ferroelectrics, since it is fully CMOS compatible. Theferroelectric phase is stabilized by doping with various dopants. Furthermore, a mixture ofhafnium and zirconium oxide (Hf1-xZrxO2) does also stabilize the ferroelectric phase.In this thesis, hafnia and zirconia based ferroelectrics are deposited by a novel CSD (chemicalssolution deposition) process and are characterized in respect to their ferroelectric, piezoelectric and pyroelectric properties. The ferroelectric nature of hafnium oxide is shown for severaldopants as well as for Hf1-xZrxO2 with different compositions and for pure ZrO2. Especially inthe case of ZrO2 this is very surprising since ZrO2 was studied for many years and for severalapplications without revealing ferroelectric properties. In contrast to atomic layer deposition(ALD), which is most commonly used for the deposition of hafnia and zirconia basedferroelectric film, the CSD technique is appropriate for deposition of thicker films without a strong reduction of the ferroelectric response. This makes hafnia and zirconia basedferroelectrics suitable for applications, where larger film thicknesses are unavoidable such aspiezoelectric and electrocaloric cooling devices

Dependence of the SET switching variability on the initial state in HfO x -based ReRAM

For any application of redox-based resistive switching devices understanding of variability is of major interest. In this work, we analyze the dependence of the SET switching time in pulse measurements of TiN/HfOx/Pt devices on the initial state before switching. The distribution of the measured SET times covers up to seven decades in one cell. A stochastic as well as a deterministic variability component are identified by relating the initial HRS resistance – obtained from a READ pulse and from the SET pulse for comparison – to the SET time. The different resulting correlations to the SET time for the two descriptions of the initial resistance are analyzed and linked to the polarity and voltage dependence of the HRS. In addition, the origin of the resistance variation is discussed

Comparison of hafnia and PZT based ferroelectrics for future non-volatile FRAM applications

Overview of sampling sites. The pictures show some of the 21 sampling sites, from which slugs were collected, including six parks (A-F) and four compost heaps (G, H, J, K). Picture I shows a slug on compost. The other sampling sites are shown in Additional file 3. Letters in brackets refer to the code used for the individual sampling sites (Table 1)