UK-based Oxford Instruments says that a world-first non-destructive quality control method developed by the UK’s National Physical Laboratory (NPL) has enabled it to commercialize wafer-scale fabrication technology for the two-dimensional (2D) semiconducting material molybdenum disulphide (MoS2).
While graphene was the first 2D material to be studied in detail, there is now also a focus on other 2D materials with diverse properties and new applications. Among these, single-layer MoS2 is generating interest due to electronic and optical properties that could pave the way for next-generation electronics and optoelectronics devices.
To commercialize electronic devices made of 2D materials, industry faces a challenge to carry out quality control checks without destroying or damaging the material. As a single layer of a 2D material is only a single atom or molecule thick, assessing its quality so far has only been possible using destructive techniques. Defects are expected to critically impact the performance of MoS2-based electronic devices, so the ability to investigate and quantify the number of defects without causing damage is crucial for enabling large-scale manufacture of the material, device fabrication and material functionalization.
Oxford Instruments sought to develop a new deposition system and process that could produce MoS2in a more industrially scalable manner to help further the commercialization of MoS2. The researchers needed a suitable quality control approach, and turned to NPL’s National Graphene Metrology Centre (NGMC), which has experise in the characterization and measurement of 2D materials.
“We were investigating the use of Raman spectroscopy for characterizing MoS2 and found that it is a viable high-throughput and non-destructive technique for quantifying defects,” says Dr Andrew Pollard, senior research scientist at NPL. “Importantly for this study we could controllably introduce known defects into MoS2 as a first step, using a technique from our previous work in graphene,” he adds.
“We were able to use NPL’s industrially focused research as a framework for developing our own quality control measure that uses Raman spectroscopy to quantify defects in MoS2 produced using chemical vapour deposition (CVD),” notes Dr Ravi Sundaram, senior scientist at Oxford Instruments. “While such techniques are widely used for graphene, there was no established way of checking the quality of MoS2 in a non-destructive manner before NPL’s work was published,” he adds. “Being able to measure the quality of the material enables us to optimize the growth process. This ensures we are able to provide very high-quality, low-defect-density MoS2 films from our tools.”
NPL’s work on MoS2 provided Oxford Instruments with the methodology needed to develop its own quality control process, which characterizes the 2D MoS2 layers without having a destructive impact on the material’s structure. This enables the team to efficiently characterize the MoS2 produced via an industrially scalable technology, helping to accelerate the commercialization of 2D materials.
“We have both academic and industry customers who are looking for efficient production and characterization of these novel materials,” says Ravi. “MoS2 is a promising material for electronics, and quite a few industries are interested in it. Being able to manufacture it efficiently is vital to making the material commercially viable and attractive, and this technique has helped us offer a high-quality and competitive product to our customers.”
MoS2 shows promise in both electronics and optoelectronics. Its inherently thin atomic structure not only offers several advantages in scaling down traditional electronics but also opens up the possibility of adding further functional elements on a chip for applications such as sensors. In addition, its semiconducting electronic structure renders it interesting for optical applications such as photovoltaics and light emission. As such, scaling up the MoS2 production and assessing its quality using non-destructive approaches offers vast benefits not only to manufacturers, but also to the industry as a whole, says the firm.