Zr-doped HfOx high-k gate dielectric films with TiN gate electrode were sputter deposited on 1 nm SiO2 or SiOxNy interface layer. Electrical properties including the equivalent oxide thickness, flat band voltage, interface state density, and the oxide charge trapped density of the MOS capacitors were investigated with respect to fabrication parameters such as Zr doping condition, post deposition annealing ambient, and type of bottom interface layer. Excellent electrical properties were obtained for films deposited at low sputtering powers. An equivalent oxide thickness of 1.7 nm was achieved for Zr-doped HfOx on a 1 nm SiO2 interface. The leakage current is four orders of magnitude lower than that of the SiO2 film. The magnitude and polarity of the flat band voltage is influenced by the high-k film deposition method, the dopant concentration, and the post deposition annealing condition. With the same SiOxNy interface layer, the Zr-doped film has a lower leakage current and a smaller interface density of states than the undoped film.

Since the installation of an ITER-like wall, the JET programme has focused on the consolidation of ITER design choices and the preparation for ITER operation, with a specific emphasis given to the bulk tungsten melt experiment, which has been crucial for the final decision on the material choice for the day-one tungsten divertor in ITER. Integrated scenarios have been progressed with the re-establishment of long-pulse, high-confinement H-modes by optimizing the magnetic configuration and the use of ICRH to avoid tungsten impurity accumulation. Stationary discharges with detached divertor conditions and small edge localized modes have been demonstrated by nitrogen seeding. The differences in confinement and pedestal behaviour before and after the ITER-like wall installation have been better characterized towards the development of high fusion yield scenarios in DT. Post-mortem analyses of the plasma-facing components have confirmed the previously reported low fuel retention obtained by gas balance and shown that the pattern of deposition within the divertor has changed significantly with respect to the JET carbon wall campaigns due to the absence of thermally activated chemical erosion of beryllium in contrast to carbon. Transport to remote areas is almost absent and two orders of magnitude less material is found in the divertor.

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Electron traps in ALD and MOCVD HfO2 and HfSiO high-k dielectrics were investigated using both conventional DC and pulse measurements. It was found that the traps in the gate stack could be associated with defects of different activation energies and capture cross-sections. This points to potentially different origins of the electrically active defects, which can be either intrinsic or process-related. Structural non-uniformity of the high-k film, associated with grain formation and phase separation, may lead to variation of electrical properties of the gate dielectric along the transistor channel. Effects of such dielectric non-uniformity, as well as electron trapping, on the measured transistor mobility were evaluated.