Schematic of device preparation procedure using the doctor-blade, screen printing, and lamination techniques.
Photograph and schematic structure of the fabricated device.
Schematic waveforms of (a) an ESD pulse before and after application to the varistor and (b) lightning surge current.
Schematic electrical circuit based on HBM for ESD endurance tests.
(a) Schematic of the apparatus used for SSPM measurement. (b) Distributions of the surface potential and resistance of grains and grain boundaries under the application of a dc voltage. (c) Results of SSPM measurement of the Pr–ZnO varistor.
characteristics of the (a) Bi–ZnO and (b) Pr–ZnO varistors before (solid lines) and after (open circles) the application of 30 kV ESD pulses.
characteristics of the Bi–ZnO varistor before and after the application of ESD pulses with different voltages in the range of . (a) and (b) show characteristics in the forward and reverse directions, respectively. The solid lines represent the initial characteristics.
Degradation tendencies of leakage current, , and electrical nonlinearity ( and ). The solid circles and squares represent these quantities in the forward and reverse directions, respectively.
SIM images of regions between the inner electrodes of the (a) Bi–ZnO and (b) Pr–ZnO varistors.
(a) and (b) are the AFM images of the Bi–ZnO and Pr–ZnO varistors, respectively. (c) and (d) are the SSPM images of the Bi–ZnO and Pr–ZnO varistors, respectively, under a dc voltage of 8 V.
Line-scan profiles of the surface potential (open squares) and resistance (solid lines) estimated from the surface potential change in the [(a) and (b)] Bi–ZnO and [(c) and (d)] Pr–ZnO varistors.
Distributions of resistance in the (a) Bi–ZnO and (b) Pr–ZnO varistors.
Schematic band diagrams of a Bi–ZnO varistor near the cathode. Electronic band structure (a) in the absence of bias and (b) under the application of a high-voltage bias such as an ESD pulse. (c) and (d) are the electronic band structures after the application of ESD pulses with voltages equal to and greater than 8 kV, respectively. The heights of the DSB and Schottky barriers are denoted by and , respectively. The dashed line represents the path of conduction electrons under reverse bias.
Chemical compositions of Bi–ZnO and Pr–ZnO varistors.
Electrical nonlinearity ( and ), breakdown voltage , and ESD and surge current withstand capabilities.
Leakage current, breakdown voltage , and nonlinearity of Bi–ZnO varistor before and after the application of various ESD voltage pulses.
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