[paper] JART VCM v1 Verilog-A Compact

JART VCM v1 Verilog-A Compact

Model User Guide

Christopher Bengel, David Kaihua Zhang, Rainer Waser, Stephan Menzel

Electronic Materials Research Laboratory; RWTH Aachen University
Forschungszentrum Jülich

Abstract: The JART VCM v1a model was developed to simulate the switching characteristics of ReRAM devices based on the valence change mechanism. In this model, the ionic defect concentration (oxygen vacancies) in the disc region close to the active electrode (AE) defines the resistance state. The concentration changes due to the drift of the ionic defects. Furthermore, these oxygen vacancies act as mobile donors and modulate the Schottky barrier at the AE/oxide interface. In this model, Joule heating is considered, which significantly accelerates the switching process at high current levels. Since the JART VCM v1b model represents an improvement of the JART VCM v1a model, this user guide will have its focus on the JART VCM v1b model. Here, the equivalent circuit diagram (ECD) as well as some equations have been modified to explain the switching dynamics more accurately  Based on the JART VCM v1b model, a variability model was developed, which includes both device-to-device and cycle-to-cycle variability. In terms of the device-to-device variability, the VCM cells are initiated with statistical distributed parameters: filament lengths, filament radii and maximum and minimum values for the oxygen vacancy concentration in the disc. The cycle-to-cycle variability is achieved by changing the four quantities during SET and RESET. The latest extension of the JART VCM v1b also includes RTN, which is based on statistical jumps of oxygen vacancies into and out of the disc region.

Fig: Equivalent circuit diagram of the JART VCM v1b model (a) 

along with the electrical model in Verilog-A (b).

The Verilog-A code of this model can be downloaded here (Verilog-A file).
The User Guide for this model version can be downloaded here (User Guide PDF).