The effect of energetic plasma on 2D semiconductor materials

Many researchers are investigating 2D materials because of their broad range of applications in optics, electronics, and energy storage. These 2D materials, however, often get exposed to energetic plasmas during the manufacturing of devices for these applications, and they may get damaged.

Kumar et al. investigate the effect of plasma on the atomic scale structure modification and defect creation in 2D materials, which are typically only a few atoms in thickness. While there have been some prior studies of individual layers or materials, the researchers completed a systematic investigation of plasma’s effect on the heterostructures of two 2D materials and how damage and etching propagate through layers.

“The biggest surprise was that boron nitride, which is well known to form a highly stable and protective layer on top of 2D semiconductor devices, is not that protective under plasma exposure,” said author Deep Jariwala.

Specifically, the researchers found hexagonal boron nitride is an effective barrier for short plasma exposures of less than 30 seconds but is ineffective for longer exposures. They also found continuous plasma exposure is more damaging than sequential exposure.

Researchers routinely place boron nitride on graphene or other 2D materials in devices and subject them to plasma etching. “Applications for our research include better etching and protection recipes for 2D materials-based devices to avoid defects in them,” said Jariwala.

The researchers will focus on how defects in individual layers interact in these materials, since they could impact the production of new types of semiconductors, light emitters, and memory devices.

Source: “Efficacy of boron nitride encapsulation against plasma-processing of 2D semiconductor layers,” by Pawan Kumar, Kelotchi S. Figueroa, Alexandre C. Foucher, Kiyoung Jo, Natalia Acero, Eric A. Stach, and Deep M. Jariwala, JVST A (2021). The article can be accessed at https://doi.org/10.1116/6.0000874 .