Carbon-related defects in Si:C/silicon heterostructures assessed by deep-level transient spectroscopy

This paper reports on a Deep-Level Transient Spectroscopy (DLTS) study of the electrically active defects in similar to 100 nm Si: C stressors, formed by chemical vapor deposition on p-type Czochralski silicon substrates. In addition, the impact of a post-deposition Rapid Thermal Annealing (RTA) at 850 degrees C on the DLT-spectra is investigated. It is shown that close to the surface at least two types of hole traps are present: one kind exhibiting slow hole capture, which may have a partial extended defect nature and a second type of hole trap behaving like a point defect. RTA increases the concentration of both hole traps and, in addition, introduces a point defect at EV + 0.35 eV in the depletion region of the silicon substrate at some distance from the Si: C epi layer. This level most likely corresponds with CiOi-related centers. Finally, a negative feature is found systematically for larger reverse bias pulses, which could point to a response of trap states at the Si: C/silicon hetero-interface

Quotient probabilistic normed spaces and completeness results

Quotient spaces of probabilistic normed spaces have never been considered. This note is a first attempt to fill this gap: the quotient space of a PN space with respect to one of its subspaces is introduced and its properties are studied. Finally, we investigate the completeness relationship among the PN spaces considered

On the origin of the 1/f noise in shallow germanium p(+)-n junctions

The low-frequency noise of shallow germanium p(+)-n junctions is studied, for diodes with or without a nickel-germanide Ohmic contact. It is shown that the application of NiGe not only reduces the series resistance, resulting in a higher forward current, but also results in a lower 1/f noise at forward bias. From the observed geometry dependence, it is concluded that germanidation suppresses the 1/f noise generated in the series resistance, leaving surface-state-assisted generation-recombination at the junction perimeter as the dominant flicker noise source

Study of electrically active defects in epitaxial layers on silicon

Electrically active defects in silicon-based epitaxial layers on silicon substrates have been studied by Deep-Level Transient Spectroscopy (DLTS). Several aspects have been investigated, like, the impact of the pre-epi cleaning conditions and the effect of a post-deposition anneal on the deep-level properties. It is shown that the pre-cleaning thermal budget has a strong influence on the defects at the substrate/epi layer interface. At the same time, a post-deposition Forming Gas Anneal can passivate to a large extent the active defect states. Finally, it is shown that application of a post-deposition anneal increases the out-diffusion of carbon from a Si:C stressor layer into the p-type CZ substrate

Impact of firing on surface passivation of p-Si by SiO2/Al and SiO2/SiNx/Al stacks

Firing impacts on surface passivation provided by a SiO2 and SiO2/SiNx stack with evaporated Al films are studied by capacitance-based techniques on MIS capacitors. For devices with insulator layers consisting solely of as-deposited SiO2, the densities of either interface states (Dit) or fixed charges (Qfc) are hardly influenced by firing. Capping the SiO2 layer with a SiNx layer results in a shift of the peak activation energy of Dit toward the valence band (Ev) of Si. Firing this SiO2/SiNx stack leads to an increase of Qfc, a reduction of Dit, and a moderate shift of peak activation energy of Dit toward Ev. Co-firing with the Al film on top significantly reduces the Qfc, Dit, and Dit peak activation energy, which is resulting from the atomic hydrogen passivation. These results are of particular interest for the development of solar cells with rear surface passivation and local contacts

Effect of schottky barrier alteration on the low-frequency noise of InP based HEMTs

For the first time the effect of increasing the Schottky barrier's Al content of InP-based InAlAs-InGaAs HEMTs from 48 to 60% on the low-frequency (LF) drain and gate current noise is investigated. It is shown that the LF gate current noise SIG(f) for the 60% case decreases by almost three decades, while the LF drain current noise S IDS(f) stays at the same level. From small coherence values, it can be concluded that drain and gate noise sources can be treated separately which facilitates the LF noise modeling of these HEMT

Investigation of pre-existing and generated defects in non-filamentary a-Si/TiO2 RRAM and their impacts on RTN amplitude distribution

An extensive investigation of the pre-existing and generated defects in amorphous-Si/TiO2 based non-filamentary (a-VMCO) RRAM device has been carried out in this work to identify the switching and degradation mechanisms, through a combination of random-telegraph-noise (RTN) and constant- voltage-stress (CVS) analysis. The amplitude of RTN, which leads to read instability, is also evaluated statistically at different stages of cell degradation and correlated with different defects, for the first time. It is found that the switching between low and high resistance states (LRS and HRS) are correlated with the profile modulation of pre-existing defects in the ‘defect-less’ region near the a-Si/TiO2 interface. The RTN amplitude observed at this stage is small and has a tight distribution. At longer stress times, a percolation path is formed due to defects generation, which introduces larger RTN amplitude and a significant tail in its distribution