The IBM/TENN/TULANE/LLNL/LBL Beamline 8.0 at the advanced light source combining a 5.0 cm, 89 period undulator with a high-throughput, high-resolution spherical grating monochromator, provides a powerful excitation source over a spectral range of 70-1200 eV for surface physics and material science research. The beamline progress and the first experimental results obtained with a fluorescence end station on graphite and titanium oxides are presented here. The dispersive features in K emission spectra of graphite excited near threshold, and found a clear relationship between them and graphite band structure are observed. The monochromator is operated at a resolving power of roughly 2000, while the spectrometer has a resolving power of 400 for these fluorescence experiments. Q

When epitaxial graphene layers are formed on SiC͑0001͒, the first carbon layer ͑known as the "buffer layer"͒, while relatively easy to synthesize, does not have the desirable electrical properties of graphene. The conductivity is poor due to a disruption of the graphene bands by covalent bonding to the SiC substrate. Here we show that it is possible to restore the graphene bands by inserting a thin oxide layer between the buffer layer and SiC substrate using a low temperature, complementary metal-oxide semiconductor-compatible process that does not damage the graphene layer.

Sophisticated microelectromechanical systems for device and sensor applications have flourished in the past decade. These devices exploit piezoelectric, capacitive, and piezoresistive effects, and coupling between them. However, high-performance piezoresistivity (as defined by on/off ratio) has primarily been observed in macroscopic single crystals. In this Letter, we show for the first time that rare-earth monochalcogenides in thin film form can modulate a current by more than 1000 times due to a pressure-induced insulator to metal transition. Furthermore, films as thin as 8 nm show a piezoresistive response. The combination of high performance and scalability make these promising candidates for nanoscale applications, such as the recently proposed piezoelectronic transistor (PET). The PET would mechanically couple a piezoelectric thin film with a piezoresistive switching layer, potentially scaling to higher speeds and lower powers than today's complementary metal-oxide-semiconductor technology.

A process has been described which can produce a midgap tungsten gate compatible with the current and future complementary metal–oxide–semiconductor technology. The tungsten was deposited directly onto a 3.0 nm SiO2 gate dielectric without measurable degradation of any of its electrical properties. The tungsten deposition process yields no reactive or corrosive by-products that affect the gate dielectric integrity. The tungsten film is found to be pure within the limits of several analytical techniques and the resistivity of the tungsten films was found to be within a factor of 2 of the bulk value.

The Si/SiO2 interface in 100-nm-thick chemical vapor deposition (CVD) tungsten gate metal–oxide–semiconductor (MOS) structures exhibits high interface state densities (Dit0>5×1011/cm2 eV) after conventional forming gas anneals over varying temperatures and times. In this letter, we show this is a consequence of the low diffusivity and solubility of molecular hydrogen in tungsten and the high temperature CVD process. We have discovered that atomic hydrogen is more effective in passivating tungsten gate MOS interfaces because of its higher diffusivity in tungsten. Atomic hydrogen can be produced (1) by the reaction of aluminum with water vapor when aluminum is evaporated on the top of tungsten, (2) by hydrogen implantation, and (3) by hydrogen plasma. These techniques can passivate the Si/SiO2 interface effectively in MOS structures (Dit0<5×1010/cm2 eV) with 100-nm thick CVD tungsten gates.

An analysis of the dynamics of degradation of ultra-thin gate S i 0 2 films under accelerated high voltage stress, from the growth of defect concentration up to the final phase of the oxide breakdorm, was performed on MOS samples with Tungsten 8s gate material. INTRODUGnONMetal gates are considered a promising approach to increase transistor tranmduotance and to reduce gate resistance [I].Tungsten in particular, being a midgap work-function material, is considered particularly useful in the case of short channel fully depleted SO1 CMOS circuits. To introduce W, in addition to major technological challenges to be solved, concerns related to the reliability of the MOS stacks have to be taken into consideration. Moreover, the study of the reliability of metal gates with Si02 is in itself particularly interesting for the basic understanding of the dielectric breakdown (BD) phenomenon. In fact, according to the physical models most accepted and most adherent to the experimental observations concerning oxide degradation under high field stresses (anode hole injection and hydrogen release model [2]), the anode material plays a major role in the oxide w e a r a t . &e would expect that by changing the anode, both anode hole injection and hydrogen mlea~e should substantially vary. So oxide wear-out kinetics should depend on the gate material in stresses where the anode is the gate.Moreover, experimental evidences suggest that with poly-Si gates also the BD event in itself, i.e. the degradation of the initial BD spot leading to the final transistor failure (hard breakdown), has at low voltage the same physical mechanism that produces the oxide degradation 131. So this means that, again, the anode material should play a major role in the BD build-up rate kinetics. In addition, at high voltage there is a transition in the BD mode in which the failure becomes extremely fast [4]. The measurement of the voltage threshold at about 4 V has indicated a number of possible physical mechanisms involving a threshold energy of about 4 eV and responsible forthe BD mnaway.In order to check such aspects we have investigated the behaviour of two different anode materials: tungsten and poly-Si gates (both p+ and n+). The latter is used as reference. In this report we show the main results. EXPERIMENTAL Most of the work here reported refers to samples consisting in nand p M O S capacitors With gate material either tungsten or poly-Si (used BS control), oxide thickness ranging from 2 to 4 nm, and with Q78M4315-XA41$M.W@ZXl4 IEEE 122(100) oriented Si substrates. The analyzed combination of gate materials and substrates are therefore n+ poly-Si / p s i , W / p-Si, p+ poly-Si /"-Si, and W /"-Si.The evolution of the oxide degradation was investigated by monitoring both the growth of defect concentration up to the oxide breakdo-and the evolution of the initial BD spot toward hard BD. All MOS capacitor samples were stressed in accumulation with consecutives pulses at constant voltage (CVS) of duration ranging from IO" s up to IO" s. After each puls...

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We describe a simple method to detect the formation of graphene during Si sublimation from SiC surfaces at elevated temperature. The method exploits differences in the thermionic emission current density between graphene and SiC. When graphene forms, the thermionic current from the sample increases by a factor of about 20. The increase in thermionic emission can be detected in situ using a biased plate located near the sample. The ability to detect when graphene forms during processing is useful in optimizing graphene synthesis processes.