Ultrahard carbon nanocomposite films

Abstract

An improved charge separation technique for metal-oxide-silicon (MOS) capacitors is presented which accounts for the deactivation of substrats dopants by hydrogen at elevated irradiation temperatures or small irradiation biases. Using high-frequency capacitance-voltage (C-V) measurements, radiation-induced inversion voltage shifts are separated into components due to oxide trapped charge, interface traps and deactivated dopants, where the latter is computed from a reduction in Si capacitance. In the limit of no radiation-induced dopant deactivation, this approach reduces to the standard midgap charge separation technique used widely for the analysis of roomtemperature irradiations. The technique is demonstrated on a p-type MOS capacitor irradiated with 60Co y-rays at 100 "C and zero bias, where the dopant deactivation is significant.Midgap charge separation is a technique widely used to distinguish the contributions of oxide trapped charge and interface traps to radiation-induced threshold (or inversion) voltage shifts in metal-oxide-silicon (MOS) devices.1 The technique owes its popularity to uncomplicated anaIysis and simple implementation, requiring only high-frequency capacitance-voltage (C-V) measurements for capacitor structures or current-voltage measurements for transistor structures. Assuming charge neutrality of the interface traps when the Fermi energy is at midgap,2 radiation-induced shifts in the midgap voltage are attributed to oxide trapped charge, while stretchout of the inversion and midgap voltages is attributed to interface traps. Among other simplifications, the technique assumes that the concentration of electrically active substrate dopants is constant with total dose.Due to the completing of hydrogen with substrate dopants, this assumption of constant doping concentration is often violated for irradiations of p-bulk devices performed _under low electric fields or at elevated temperatures.3 Hydrogen released in the oxide during irradiation is known to neutralize many types of shallow acceptors (especially B) in Si primarily through two mechanisms.4]3 In the case of acceptor passivation,4-8 Ho can deactivate B-by occupying a bond-centered position along a <111> axis between a substitutional B site and a neighboring Si atom. In the case of acceptor compensation,9-13 electron-hole pair recombination occurs when Ho donates an electron to the Si conduction band and ionically bonds to B-. For either mechanism, the result is a reduction in the net concentration of electrically active dopants and a decrease in the semiconductor capacitance. In this letter, we present an improved charge separation technique for MOS capacitors, which accounts for the deactivation of substrate dopants by radiation-released hydrogen.To illustrate its utility, the technique is demonstrated on a test capacitor from a radiation-hardened bipolar complementary metal-oxide-silicon process developed by Analog a}El~~L~o~iC Mail scwitcz@ sandia.gwDevices. The capacitor is fabricated with a 55 nm wet thermal oxide and a B-doped ...

Disorder, clustering, and localization effects in amorphous carbon

“…Siegal et al annealed nonhydrogenated a-C films produced by pulsed laser ablation and reported the presence, via high-resolution transmission electron microscopy, of regions 3 -5 nm in size that were 5-10 % more dense that the surrounding regions. 27 The as-deposited films have stresses of 5 -7 GPa and a film density of 3.0 g cm −3 but near-complete stress relief had occurred and the density had dropped to 2.8 g cm −3 with thermal annealing to 600°C. Over the same annealing temperature range the optical transparency of the film decreased, demonstrating that clustering of the sp 2 within the film is increasing.…”

Further improving the mechanical and tribological properties of low content Ti-doped DLC film by W incorporating

“…Overall, two main reasons Page 4 of 28 A c c e p t e d M a n u s c r i p t are expected to explain it. On the one hand, high residual stress ranging from 1~10 GPa lead to spall off from metallic substrates, at the same time, limit the film thickness [6][7][8]. This one could be effectively solved by the doping elements such as Ti, Cr, W and so on [9][10][11]; On the other hand, weak adhesive strength at the boundary between the film and substrate, which could be solved by the introduction of the addition Me, Me X C, Me X N interlayer [12][13][14].…”

Spatially resolved energy dispersive x-ray spectroscopic method for in-situ evaluation of mechanical properties during the growth of a C - Pt composite nanowire

“…5 Nanocomposite or bilayer nanomaterials have interesting mechanical, electrical, optical and magnetic properties. [6][7][8][9][10][11] In the past, composite nanomaterials have been fabricated by electrochemical deposition, 12 sputter deposition 5 and FIB/FEB-CVD methods. We report here a method using FIB-and FEB-CVD processes to fabricate C-Pt core-shell like composite nanomechanical structures, consisting of a carbon nanowire core surrounded by a platinum outer layer shell.…”