1,721,217 research outputs found
Space-Charge Limitations of Tunneling Resonances
No full textA simple explanation is presented for the large quantitative discrepancies between theory and experiments regarding the effects of tunneling resonances in suitably designed, double-barrier heterostructures. It is suggested that the main limitation is due to the maximum amount of charge that can be accomodated on the resonant level without taking it out of the resonance energy-alignment condition. As this is normally much less than that required for a fully developed resonance, the experimental effects are proportionally reduced. © 1986
Dynamic Effects in the Detection of Bridging Faults in CMOS ICs
No full textDynamic effects in the detection of bridging faults in CMOS circuits are taken into account showing that a test vector designed to detect a bridging may be invalidated because of the increased propagation delay of the faulty signal. To overcome this problem, it is shown that a sequence of two test vectors , in which the second can detect a bridging fault as a steady error, can detect the fault independently of additional propagation delays if T0 initializes the faulty signal to a logic value different from the fault-free one produced by T1. This technique can be conveniently used both in test generation and fault simulation. In addition, it is shown how any fault simulator able to deal with FCMOS circuits can be modified to evaluate the impact of test invalidation on the fault coverage of bridging faults. For any test vector, this can be done by checking the state of the circuit produced by the previous test vector. © 1992 Kluwer Academic Publishers
A Novel Critical Path Heuristic for Fast Fault Grading
No full textThis work presents a new fault grading heuristic based on the critical path tracing technique that tackles the problems associated to fan-out reconverging nodes (FORN's) without using forward propagation of the fault effects. To determine the criticality status of a fanout reconverging node that can differ from that of its fan-out branches (FOB's), we use the concepts of evidencing and masking paths. Using the statistics from exact fault simulations, heuristic rules are derived for the generation of masking and evidencing paths. The results obtained on benchmark circuits show: a) good accuracy on fault coverage estimate; b) computation time linear in the number of gates and comparable to that of the fault-free simulation. © 1991 IEE
On the Determination of the Si-SiO2 Barrier Height from the Fowler-Nordheim Plot
No full textIn this paper it is shown that, even considering a field-dependent Si–SiO2 barrier height for electron tunneling as predicted by the quantum-mechanical (QM) modeling of Si–SiO2 interfaces, the Fowler–Nordheim (F-N) plot is linear. It is proven that the “equivalent” barrier height extracted from the graph slope is not representative of the actual field-dependent barrier. The problem of correctly estimating the oxide field to be used in F-N plots is also addressed. © 1991 IEE
Influence of Localized Latent Defects on Electrical Breakdown of Thin Insulators
No full textElectrical breakdown in thin SiO2, films is measured with different techniques at different electric fields. It is shown that oxide reliability is affected by the presence of latent defects requiring a certain time to develop and evolve towards a destructive stage. As such a time is weakly dependent on applied fields, breakdown is not adequately detected by accelerated tests. It is also shown that, due to the localized nature of breakdown, meaningful relationships between measured parameters able to clarify the microscopic nature of oxide failure are not easy to establish. © 1991 IEE
Quantum-Mechanical Modeling of Accumulation Layers in MOS Structures
No full textAn original method is used for the quantum-mechanical modeling of n-type silicon accumulation layers. Contrarily to previous methods, which were only valid near 4.2 K, our approach is valid up to room temperature and beyond. The obtained self-consistent results are compared with those of the standard classical model for the accumulation layer, and the differences between them are found to be relevant for the modeling of important device applications. In particular, it is shown that the semiconductor voltage drop and the oxide barrier height for Fowler-Nordheim (F-N) tunnel injection are largely modified by the quantization of the accumulation layer. The dependences of these two magnitudes (accumulation voltage drop and effective F-N barrier height) on oxide electric field and substrate doping are reported. Experimental F-N current-voltage characteristics of production-quality -Si(n)/Si02/poly-Si(n+) MOS capacitors are used to validate the presented quantum ..
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