Obtaining Few Layers Tellurene Through Controlled Oxygen Annealing*

Tellurene (Te) exhibits extraordinary properties such as tunable bandgap, anisotropic behavior, and resilience to ambient conditions, making it a desirable material for electronics and photoelectronic applications. However, exfoliation of a few layers of Te nanosheets can be challenging, leading to low yield. In this work, we show Te thinning using a thermal annealing technique applied on thick Te nanosheets. According to our AFM characterization, a considerable decrease in thickness was measured, with a decrease larger than 500nm. Raman spectroscopy was also used to identify the change in thickness of these thinned Te nanosheets. We observe a blue shift for A1 and E2 Raman modes after thinning, confirming the change in thickness of these nanosheets. Nevertheless, our method shows that thinning is non-uniform where a favorable thinning direction is observed for all Te nanosheets. This behavior can be attributed to the anisotropy behavior of Te, where thinning occurs along the major axis. Our results shed some light on an annealing method to thin Te nanosheets for future device applications.