Schottky Emission Through Thin Insulating Films

Abstract

With the discovery of observable tunnel emission through thin insulating films, much attention has been focused on this mechanism of current transfer. The importance of space-charge limited current in somewhat thicker films has also been recognized. We have recently observed a third mechanism of current transfer, namely, the high-fie Id emission of hot electrons from a metal into the conduction band of an insulator in contact with it; this process is identical with Schottky emission into the vacuum. 1 The system consists of a thin insulating layer J between two metals M x and M 2 , a voltage V being maintained between the metals (see Fig. 1). The work function between / and M x is <p x ; the actual potential seen by an electron passing from M x to / is shown by the dashed line; it differs from the conduction band level by virtue of the image forces between the electron in the insulator and the metal. An electron in the metal with a forward energy greater than the potential maximum can enter the conduction band of the insulator, and hence give rise to a current between the two metals. Conduction bandFermi level .1 FIG. 1. Energy level diagram of system described in text,The current-voltage and current-temperature relationships for the three transfer mechanisms mentioned above are given in Table I. The constants in the expression for Schottky currents are P=(q 3 /Ka) l/2 /kT, a=ATe ^where q is the charge on the electron, a is the Table I. Current-voltage and current-temperature dependences for the three transfer mechanisms. Mechanism Current-voltage dependence Current-temperature dependence Space-charge limited Tunnel emission Schottky emission /ocy2 I<*V for V <(p . Tr 2 -const/y _ . . , " /a v x e for high V l/2\ 1=0? exp(pv lu ) /ccpi* the mobilitv of electrons in the insulator None /oc r 2 e -const/T

Injected Electron Currents Through Insulators

“…Theexpressions (18), (20)) and (21) in Section5 apply for arbitrary barriers, the magnitudes b, C, f , U,, E , and T, being dependent on the barrier shape. An exact calculation with the image force barrier, if possible, is of questionable value, because potential (5) is incorrect near the metal surfaces [31] (see also [lo]).…”

Photoconductivity and photo-detection response of multiferroic bismuth iron oxide

“…In the literature several conduction mechanisms have been proposed to find out for conduction in the dielectric: Schottky emission (SE), Poole-Frenkel emission (PF), and space charge limited conduction (SCLC). [22][23][24] These three basic mechanisms represent the interface, bulk, and freecharge carriers injection as function of applied external fields and temperatures, respectively. In case of SE, log (I/T 2 ) vs V 1/2 should gives a straight line having slope near to the optical dielectric constant of the materials.…”

Enhanced bipolar resistive switching behavior in polar Cr-doped barium titanate thin films without electro-forming process

“…The aforementioned increment in the slope in the LRS leads to investigate the Schottky conduction mechanism. 36 The current-voltage plot was re-plotted as ln J vs. E 1/2 and linearly fitted as shown in Fig 3(b). The relationship between the current density and applied electric field in Schottky emission conduction is given below,…”