Laser-induced grayscale patterning in TeOx thin films

Grayscale patterns have been widely studied and applied in many fields. In this paper, grayscale patterns with precise grayscale changes are fabricated on TeOx thin film by laser pulse with respective wavelengths of 635 and 405 nm. Two obvious changes according to the different grayscale level emerge as laser energy increases. The first change is from invisible to white-grayscale with low laser pulse width between 2 ns and 50 ns. After a transient period with laser pulse width between 48 ns and 55 ns, the grayscale in the second change becomes darker and darker following the laser pulse width increases from 56 ns to 250 ns. The mechanism of the grayscale change is partly explained and verified by TEM, which involves the agglomeration and segregation of Te, crystallization and recrystallization after melting of Te and TeO2, and ablation of TeOx, wherein different mechanism is dominant in each stage. We can obtain grayscale patterns with precise grayscale changes to meet specific requirements by controlling the parameters precisely.