Analysis of Grain Boundary Effects Based on Location in a Diode-Type NAND Flash Memory Cell

In this paper, we investigate the variation in turn-on voltage <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\boldsymbol{V}_{\mathbf{on}})$</tex> depending on the grain boundary (GB) position within the cell during the read operation of diode-type NAND flash memory, which achieves an extremely steep subthreshold swing (SS) through a positive feedback (PF) mechanism. During the read operation, as the GB is positioned further from the center of the selected cell, it becomes less influenced by the gate bias. Depending on the presence of the electron barrier, holes and electrons are trapped at the GB, resulting in variation in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{V}_{\mathbf{on}}$</tex>.