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We report the results of total ionizing dose radiation tests on germanium-substrate MOS capacitors with Hf[O.sub.2]/[Dy.sub.2] [O.sub.3] gate dielectrics with effective oxide thicknesses of ~1.9 and 1.1 nm. There are significant densities of border traps before irradiation, and no measurable changes in device response after 10 Mrad(Si[O.sub.2]) exposure. We attribute the lack of net oxide charge trapping to equal electron and hole trapping and/or charge neutralization via gate leakage current. The introduction of [Dy.sub.2] [O.sub.3] evidently leads to reduced charge trapping in these Hf[O.sub.2]/[Dy.sub.2] [O.sub.3] dielectrics relative to devices with only Hf[O.sub.2]. Index Terms--Border traps, dysprosium, germanium MOS capacitors, Hf[O.sub.2], high-K dielectric, total dose radiation effects, ultrathin gate oxide.

The evaluation of the Ce[O.sub.2]/Hf[O.sub.2] material combination as a candidate gate dielectric for Ge transistors is discussed. It is observed that Ce[O.sub.2] acts as a good passivating layer for Ge, while small diode surface leakage currents are also found.

Magnetron sputtered carbon thin films were studied to determine the effect microstructure on their conductivity.

Amorphous-carbon films grow on n or p type single crystal silicon were studied for structural, electrical and low frequency noise characteristics.

Amorphous carbon thin films were studied and low-frequency noise measurements were undertaken.

The chemical stability of La-containing passivating layers /high-k gate stacks on Ge substrates is investigated by x-ray photoelectron spectroscopy. It is found that upon exposure to oxygen, a La-covered Ge surface spontaneously converts to a stable LaGeOx passivating layer. However, in the presence of overlying metal layers such as Al and Hf or upon deposition of high-k metal oxide cap layers such as Al2O3 and HfO2, the LaGeOx layer strongly reacts with the overlayers forming LaAlOz and LaHfOz compounds. In the case of Al or Al2O3, the LaGeOx is completely dissociated, while in the case of Hf or HfO2, LaGeOx remains although with a change in composition. The results are interpreted in terms of oxygen densification according to which the strongly electropositive La drives the reaction toward the formation of oxides with the highest oxygen density. The results suggest that HfO2 has a better chemical compatibility with LaGeOx making it more suitable for the gate stack. [ABSTRACT FROM AUTHOR]

Ge-doped ZrO2 thin films are prepared on SiON/Si substrates by atomic oxygen beam deposition. It is shown that, at low growth temperatures (225–360 °C) and by using only a low amount of Ge (3–6.2 at. %), it is possible to develop a pure tetragonal zirconia phase, which remains stable after 1050 °C annealing in N2. The dielectric permittivity (k) shows pronounced correlation with the structural details of the oxide film and is increasing with Ge content to a maximum value of 37.7, which is obtained for a 6.2 at. % Ge-doped sample grown at 225 °C. The dielectric permittivity enhancement upon doping is attributed to the increase in the ZrO2 tetragonal distortion, as inferred from x-ray diffraction data. Obtaining tetragonal ZrO2 with very high k-values at low deposition temperatures and with excellent thermal stability could be beneficial for the integration of this dielectric in scaled devices requiring low equivalent oxide thickness. [ABSTRACT FROM AUTHOR]

Germanium metal-insulator-semiconductor capacitors with La2O3 dielectrics deposited at high temperature or subjected to post deposition annealing show good electrical characteristics, especially low density of interface states Dit in the 1011 eV-1 cm-2 range, which is an indication of good passivating properties. However, the κ value is estimated to be only about 9, while there is no evidence for an interfacial layer. This is explained in terms of a spontaneous and strong reaction between La2O3 and Ge substrate to form a low κ and leaky La–Ge–O germanate over the entire film thickness, which, however, raises concerns about gate scalability. Combining a thin (∼1 nm) La2O3 layer with thicker HfO2 degrades the electrical characteristics, including Dit, but improves gate leakage and equivalent oxide thickness, indicating a better potential for scaling. Identifying suitable gate dielectric stack which combines good passivating/interfacial properties with good scalability remains a challenge. [ABSTRACT FROM AUTHOR]

Ge-doped Zr[O.sub.2] thin films are prepared on SiON/Si substrates by atomic oxygen beam deposition and a pure tetragonal zirconia phase is developed. Obtaining tetragonal Zr[O.sub.2] with very high k-values at low deposition temperatures and with excellent thermal stability is beneficial for the integration of this dielectric in scaled devices requiring low equivalent oxide thickness.

The dielectric quality of [La.sub.2][O.sub.3] and its interface with Ge is examined as a function of growth temperature and postdeposition annealing (PDA) conditions. [La.sub.2][O.sub.3] has played the role of an efficient passivating layer in more complex gate stacks for Ge devices.

In the present study we investigate the structural, Fermi surface and optical properties of the recently synthesized (ZrTi)AlC MAX phases using density functional theory. The inclusion of Ti in the M site causes a reduction of both the a and c lattice parameters. The reduction of the a lattice parameter with respect to Ti content is more significant and this is reflected in the increase of the c/ a ratio. The Fermi surfaces are formed mainly due to the low-dispersive transition metal d-like orbitals, which are responsible for the conductivity in the compounds. The energy loss spectra reveals that the two end members of (ZrTi)AlC ( x = 0 and 3) change from metallic to dielectric response at incident light energies 11.9, 13.4 and 10.8, 13.5 eV for [100] and [001] polarization directions, respectively. The reflectivity spectra indicate the ability of two end compounds ZrAlC and TiAlC to be candidate materials for coatings to reduce solar heating. The calculated optical functions show the dependence on the polarization directions. [ABSTRACT FROM AUTHOR]

Diffusion properties are technologically important in the understanding of semiconductors for the efficent formation of defined nanoelectronic devices. In the present study we employ experimental data to show that bulk materials properties (elastic and expansivity data) can be used to describe gold and silver diffusion in germanium for a wide temperature range (702-1177 K). Here we show that the so-called cBΩ model thermodynamic model, which assumes that the defect Gibbs energy is proportional to the isothermal bulk modulus and the mean volume per atom, adequately metallic diffusion in germanium. [ABSTRACT FROM AUTHOR]