Impact of Grain Sizes on Programmable Memory Characteristics in Two-Dimensional Organic-Inorganic Hybrid Perovskite Memory.

Recently, organic-inorganic hybrid perovskites (OIHPs) have been used in resistive switching memory applications because of current-voltage hysteresis that originated from ion migration in the perovskite film. As the density of the memory devices continues to increase, the size of the devices approaches that of the individual grains of the polycrystalline films. Thus, the effects of the grain boundary and the grain size will become important to investigate the influence on the switching behaviors. Here, we report the effects of grain sizes on the resistive switching property of (C4H9NH3)2PbBr4 (BA2PbBr4) films. The BA2PbBr4 films were formed by using sequential vapor deposition. First, a lead bromide (PbBr2) film was deposited by thermal evaporation, and then the film was exposed to organic vapor to form BA2PbBr4 films. The grain sizes were controlled by changing the transformation temperatures ( TT = 100, 150, and 200 °C). When the TT values were 100, 150, and 200 °C, the grain sizes of BA2PbBr4 were ∼180 nm, ∼1, and ∼30 μm, respectively. In the memory device based on BA2PbBr4, the off current decreased from ∼10-4 to ∼10-8 A as the grain size increased from ∼180 nm to ∼30 μm. This method to synthesize BA2PbBr4 films provides a simple way to control the grain sizes, and understanding of the effects of grain sizes on memory characteristics will provide an insight to improve the reliability of the OIHP-based memory as the electronic devices are scaled down to the sizes of grains.