Choosing Between 2D and 3D Materials to Set Off the Commercialization of Next-Gen Semiconductors

July 18, 2020 by Gary Elinoff

South Korean Researchers fabricate a new type of nonvolatile memory based on halide perovskite materials.

Researchers at Pohang University of Science and Technology (POSTECH) exploit resistive switching property in halide perovskite materials to develop the basis for a new type of fast, low-power, nonvolatile memory. 

Halide perovskite materials exhibit a resistive switching property, which means that with the application of a voltage, the substance's resistance will change.

The change happens quickly, it requires little power, and most importantly, the resistive value is unchanging until it's hit with an opposite pulse. This property can potentially be based on a new type of Resistive Random Access Memory or ReRAM. 


What are ReRAMs?

Resistive Random Access Memory (ReRAM) is a type of nonvolatile memory. Unlike semiconductor memory, ReRAMs record ones and zeros by changes in resistance. 

The resistive value that is read across the terminals of the device changes from low to high, or from high to low depending on the applied voltage; in the absence of another voltage pulse, the resistance, and therefore the one or zero states of the device, doesn't change, hence the component's non-volatility. 

We have previously reported on the memristor, which is a well-known type of ReRAM.

Material scientists have been devoting much interest to perovskites of late, and we have recently reported on their potential uses in energy storage. However, the material's employment in-memory technology has been hampered by its poor stability when they are exposed to the atmosphere. The scientists sought to overcome poor stability by searching for a more optimal type of halide perovskite material.


Design of hallide pervoskite materials for resistive switching memory.

Image credited to POSTECH


First-Principles Calculations

The team employed first-principles calculations, a method based on quantum mechanics, to determine a most likely material candidate. The results predicted CsPb2Br5, an inorganic perovskite of a two-dimensional layered structure, to be a strong contender.

The two-dimensional CsPb2Br5 was synthesized by the team and was compared to a three-dimensional structure, CsPbBr3. The 3D material lost its memory characteristics at temperatures higher than 100 °C.

However, the 2D layered-structure of CsPb2Br5 maintained its memory characteristics at temperatures of over 140 °C. Moreover, the 2D material could be operated on at voltages lower than one volt, which is an important finding given the consistent trend towards ever lower operating voltages in modern electronic systems. 

As noted by the lead investigator, Professor Jang-Sik Lee, "Using this materials-designing technique based on the first-principles screening and experimental verification, memory devices' development can be accelerated by reducing the time spent on searching for new materials. This is expected to accelerate the commercialization of next-generation data storage devices." 



As the investigators point out, "It takes just a few seconds to download a 30-minute video clip, and you can watch a show within 15 minutes after it airs." As such, there is a never-ending, worldwide search for stable computer memories. 

There is a proliferation of mobile, wearable, and remote IoT devices. Low power consumption is a prime design criterion for these devices, and let's not forget the unique power requirements of insatiably hungry servers of all types worldwide. It is to be hoped that devices based on 2D perovskites will represent a viable way forward in low power, high-reliability, nonvolatile memory.