Nature of the Schottky-type barrier of highly dense SnO2 systems displaying nonohmic behavior

Abstract

The electrical characteristics of highly dense SnO 2 ceramic varistors are believed to be caused by the existence of potential barriers at the grain boundary. A complex plane analysis technique ͑to eliminate the influence of trapping activity associated with the conductance term observed via depression angle of a semicircular relaxation in the complex capacitance plane͒, allied with an approached Mott-Schottky model, are used to demonstrate that the potential barriers at the grain boundary are Schottky-type barriers in SnO 2 varistors such as those observed in the traditional ZnO varistor.

Electrostatic force microscopy as a tool to estimate the number of active potential barriers in dense non-Ohmic polycrystalline SnO2 devices

“…͑1͒ combined with a complex capacitance analysis. [6][7][8] Table I presents the comparative values and other typical non-Ohmic parameters of the MOV system studied here. Therefore, ␣ and electric breakdown field ͑E b ͒ were found to be about 75 and 6900 V cm −1 , respectively.…”

“…6,7 The increase in non-Ohmic properties due to the higher degree of oxidation has already been proven to cause an increase in the mean barrier height values and in the amount of active ͑or effective͒ barriers. [6][7][8] Therefore, the number of active barriers is an important parameter for the non-Ohmic properties, mainly because they are very sensitive to structural and compositional variations. 9,10 A larger number of active barriers due to GB oxidation, for example, is the cause of decreases in leakage current.…”

“…Calculations of the GB capacitance are made from the high frequency intercept associated with high frequency relaxation in the complex capacitance plane. 8 The use of the complex capacitance plane to calculate the grain boundary capacitance is very important because the methodology separates the related GB capacitance to the other relaxation processes existing in polycrystalline materials. 8 The dependence of the applied voltage on the GB capacitance can be calculated using the equation: 11…”

Separation of dielectric and space charge polarizations in CaCu3Ti4O12∕CaTiO3 composite polycrystalline systems

“…[10][11][12] Specifically, the grain boundary barrierlayer capacitances are generally associated with non-Ohmic properties in metal oxide polycrystalline semiconductors. [13][14][15][16] Indeed, in addition to the remarkable and intriguing dielectric property, Chung et al 12 observed that potential barrier exists intrinsically in the grain boundary region, likely possessing a Schottky-type nature, according to Refs. 12 and 17.…”

Electrical and microstructural properties of microwave sintered SnO2-based varistors

“…Fig. 8 shows the capacitance behavior of the microwave barrier, which is related to the presence of oxygen species at the grain boundary [21][22][23][24]. Table III lists the parameters obtained from these graphs.…”