Centroid Extraction Research Articles

Direct Measurement of Back-Tunneling Current during Program/Erase Operation of Metal–Oxide–Nitride–Oxide–Semiconductor Memories and Its Dependence on Gate Work Function

In this study, we have established a novel scheme to extract the back-tunneling current from the transient characteristics of a metal–oxide–nitride–oxide–semiconductor (MONOS) memory capacitor during programming or erasing. Using a charge centroid extraction method, the separation of trapping current, leakage current and back-tunneling current was successfully accomplished. By studying the gate work function dependence of injected current, it was found that the leakage current due to electron injection from the Si substrate is the dominant component during deep programming and that the back-tunneling current due to electron injection from the gate electrode is the predominant component of injected current during deep erasing.

Centroid extraction and illusions of extent with different contextual flanks.

In the present study, a computational model of the automatic centroid extraction based on the processes of local integration of excitatory profiles in the visual pathways has been developed. The model predictions have been compared with the results of our psychophysical examination of the perceptual distortions of the spatial extent. In experiments, the subjects matched two spatial intervals flanked by one of the three types of the contextual objects: either the Müller-Lyer wings, or vertical stripes, or spot pairs. A good resemblance between the theoretical functions and dependencies of the illusions' magnitudes on various spatial parameters of the stimuli has provided evidence that the effects caused by indirect positional coding via centroids are powerful enough to explain the phenomena of the geometric illusions investigated.

Programme and retention characteristics of SONOS memory arrays with layered tunnel barrier

Layered tunnel barriers (T-ONO) might help circumvent retention limitations of nitride charge trapping devices (SONOS) programmed/erased by direct tunnelling without invoking high-K dielectrics in the gate stack. In order to establish to what extent the properties of a T-ONO tunnel layer influence the performance of SONOS memories, NOR memory arrays containing a silicon oxide/silicon nitride/silicon oxide T-ONO layer, a silicon nitride charge trapping layer and a silicon oxide blocking layer were fabricated and investigated. The T-ONO layer was formed using wet reoxidation of the silicon nitride, as this process is known to generate a lot of traps at the interface between silicon nitride and silicon oxide, as well as in the reoxidized portion of the silicon nitride itself. Besides standard memory measurements like programme/erase behaviour, endurance and retention, charge centroid extraction measurements were carried out in order to explain the retention behaviour and associate it with the position of the charge. It has been demonstrated that the performance of SONOS memories with a T-ONO layer strongly depends on the technological properties/quality of the T-ONO barrier which, therefore, may not be a universal solution to retention problems in SONOS devices.

Pseudoneglect: Evidence for both perceptual and attentional factors

When neurologically normal individuals bisect a horizontal line as accurately as possible, they reliably show a slight leftward error. This leftward inaccuracy is called pseudoneglect because errors made by neurologically normal individuals are directionally opposite to those made by persons with visuospatial neglect ( Jewell & McCourt, 2000). In the current study, normal right-handed observers bisected horizontal lines that were altered to bias line length judgments either toward the right or the left side of the line. Non-target dots were placed on or near the line stimuli using principles derived from a theory of visual illusions of length called centroid extraction ( Morgan, Hole, & Glennerster, 1990). This theory argues that the position of a visual target is calculated as the mean position of all stimuli in close proximity to the target stimulus. We predicted that perceptual alterations that shifted the direction of centroid extraction would also shift the direction of line bisection errors. Our findings confirmed this prediction and support the idea that both perceptual and attentional factors contribute to the pseudoneglect effect.