Platinum diselenide (PtSe2): a novel 2D material with very promising properties for applications in electronics and sensing
In ULISSES we are actively researching its use for photodetectors. Its main strength is that, in contrast to many other materials, it can be synthesized at a relatively low temperature compatible to common CMOS processing, without strict substrate requirements. We have studied the nanocrystalline nature of the material to better understand how it influences its properties and to provide insights for tailoring the material properties as desired.
The layered van-der-Waals material PtSe2, a two-dimensional noble-metal-based material from the group of the transition metal dichalcogenides, has gained an increasing amount of attention over the last years. Due to its interesting electronic, optoelectronic, and piezoresistive properties, it has been proposed for various applications in electronics and sensing, including piezoresistive pressure sensors or microphones, highly sensitive photodetectors, or gas sensors with both high sensitivity and specificity. A major advantage is the large-scale growth method called thermally assisted conversion (TAC), which yields high quality thin films of PtSe2 while at the same time staying within the temperature budget of CMOS back-end-of-line processing technology. This could imply a large step forward to potential integration within existing CMOS technology in industry.
Experiments and measurements with TAC-grown PtSe2 thin films have, however, often yielded very different results in terms of piezoresistive and (opto-)electronic properties. To investigate this issue, we have examined the nanocrystalline structure of the PtSe2 films in detail using scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. At the same time, we fabricated devices to measure the electronic and piezoresistive properties of the material.
The study allowed us to show strong correlations between the nanocrystalline structure and the electronic properties of the TAC-grown PtSe2 layers. A variation of the nano-crystallite size and orientation within the film influences the electronic properties across many orders of magnitude. At the same time, we showed that Raman spectroscopy can be used as a very helpful and fast tool to assess the material quality based on the width of the characteristic peaks of the Raman spectrum of crystalline PtSe2.
Our experiments show that very high-quality films can be produced using the large-scale synthesis approach, which is a great advantage for the integration of PtSe2-based devices in CMOS technology. Additionally, the findings suggest that by precisely controlling the synthesis conditions during PtSe2 fabrication, the material properties can not only be optimised but also be tailored according to the application needs. This makes PtSe2 a very versatile novel material for several fields of applications.
Sebastian Lukas, lead author of the paper and ULISSES researcher with AMO GmbH
Lukas, S., Hartwig, O., Prechtl, M., Capraro, G., Bolten, J., Meledin, A., Mayer, J., Neumaier, D., Kataria, S., Duesberg, G. S. & Lemme, M. C. Correlating Nanocrystalline Structure with Electronic Properties in 2D Platinum Diselenide. Advanced Functional Materials 2102929 (2021).