Transparent Microheater Enabled by Laser Perforation of the Thin CaSi₂ Film

We report highly transparent in the wide band optical range of (0.4–7) µm mesh electrodes fabricated on thin semimetal films of semimetal calcium disilicide (CaSi₂) by utilizing femtosecond laser ablation technique with flat top beam shaped geometry. Compared with continuous films, mesh electrodes demonstrate an increase in the figure of merit as transparent conducting materials from 0.3 up to 0.9 Ω^–1. Of importance, CaSi₂ retains low sheet resistance not exceeding 20 Ω/sq after laser processing. Obtained material parameters allowed testing CaSi₂ mesh electrodes under actual conditions as transparent heater. The surface temperature as high as 150°C under low applied DC voltage of 8 V has been approved by infrared camera. CaSi₂ heater possess hysteresis free behavior with response as fast as 40 s and excellent stability under the cyclic operation. Thus, laser perforated CaSi₂ thin films could be considered as a material of choice for the infrared optoelectronic applications, smart windows and miniature heaters for microscopic observations of biological samples.