Synthetic representations of the Poole Frenkel (PF) and Poole regimes

Abstract

2014 Une étude synthétique de l'ionisation de donneurs par un champ électrique est présentée afin d'apporter des éclaircissements, utiles à l'expérimentateur, sur les régimes Poole et Poole Frenkel (PF). L'accent est mis sur la similitude de certaines des hypothèses fondamentales, ainsi que sur le caractère artificiel des hypothèses spécifiques au régime Poole. Quelques ambiguïtés des représentations graphiques rencontrées dans la littérature sont aussi rapportées. De même sont mises en évidence les divergences existant entre les auteurs à propos : de la barrière de potentiel qu'ont à franchir les électrons en bas et en hauts champs ; et de la notion de champ de transition entre les deux régimes. L'exposé est essentiellement consacré au cas des puits coulombiens, bien que des puits à plus court rayon d'action soient aussi évoqués. Deux diagrammes à trois dimensions sont construits, accompagnés de simulations annexes déduites des modèles de Hill, dans le but de délimiter clairement, sur des bases quantitatives, les intervalles de validité respectifs des régimes Poole et PF, ce dernier étant. éventuellement assorti d'un effet tunnel assisté thermiquement. Abstract. 2014 A synthetic study of the field-induced ionization of donors is presented in order to bring some insights, usefull to experimentalits, into the Poole and Poole Frenkel (PF) regimes. Emphasis is made on the similarities of some of the fundamental assumptions, as on the artificial character of the hypotheses specific to Poole regime. Some ambiguities dealing with plottings met in literature are also reported. Likewise,

Impact of defect occupation on conduction in amorphous Ge2Sb2Te5

“…To extract the inter-trap distances from measured current-voltage characteristics (IV-curves), we employ a previously introduced transport model 24 45 . In this model multiple-trapping transport is combined with field-enhanced emission, building on works by Hill 11 and Pillonet 22 . We refer to the methods section for a mathematical description.…”

“…Due to this lowering, the number of charge-carriers emitted into the band and thus the conductivity increases. If the density of sites with Coulomb potentials is sufficiently high, their overlap may lead to an additional barrier-lowering 11 21 22 . For example, the defect density in amorphous GeTe, e.g.…”

High-field electrical transport in amorphous phase-change materials

“…Combining the approaches of Pillonnet and Ongaro 11 and Hill, 12 we have recently shown that a model combining multiple trapping transport 13 with spherical emission of charge carriers from a Coulomb potential can describe the succession of field transport regimes (Ohmic-Poole-PooleFrenkel (PF)) observed not only in the melt-quenched state of nanometer-scale phase-change memory cells but also in the as-deposited amorphous phase of micrometer scale (GeTe) line-cells. 14 Due to the well defined shape of the active region (i.e., the phase-change material, PCM hereafter), the latter devices are also perfectly suited to study the field dependence of the IV curve close to the switching field.…”

Frenkel-Poole Mechanism Unveils Black Diamond as Quasi-Epsilon-Near-Zero Surface

“…Such behavior was attributed to the intense trap occupation by the promotion of electrons from valence bands, causing coulomb interaction between the trap centers with subsequent barrier lowering with an estimated mean distance (λ traps ) of the electron-filled trap states of about 70 nm. The energy reduction due to the coulombic interaction of close traps additive to the electric field contribution may be related to their distance (a) with the following equation based on the Vollmann model [ 46 ]: where is the thermal potential (see Figure 9 ). Since we are not observing a transition from Poole to Frenekl-Poole conduction regimes, it is not possible to extrapolate the real traps’ distance from the I/V curves, but we can consider that, given the high extrapolated beta coefficient, FP electron emission happens at distances of hundreds of nm, thus corresponding to the spatial gap between laser induced nanowaves (see Figure 4 a and Figure 5 b).…”