Ten micron-thick undoped SnO2 layers grown by spray pyrolysis for microheater fabrication
Client: Exciton Company (http://excitonco.ir/fa/)
Director project: Prof. Faramarz Hossein-Babaei
Project type: Pilot plant implementation
Project collaborator: Mohsen Gharesi, Mohammad Ansari
Summary of project:
Micron-thick layers of tin oxide are advantageous for the fabrication of high power density transparent microheaters operating at elevated temperatures and harsh environs. In this project, 10 μm-thick SnO2 layers are grown on alumina substrates through ultrasonic spray pyrolysis deposition. Produced layers function as long life heating elements operating at temperatures as high as 1000 °C. The required ohmic contacts are formed through diffusion bonding of gold wires to the SnO2 deposits. Long term stability of the fabricated microheaters is examined in a month of continuous operation at 600 °C; the devices show only ~5% surface temperature change, demonstrating exceptional high temperature stability of the tin oxide microheaters. The thermal stability of the composition and microstructure, the negative temperature coefficient of resistance, and the proper range of sheet resistance, render the grown layers suitable for long life microheater fabrication. The device is utilized as low voltage fuel igniter in exhaust systems for combustion safety units in chemical and petrochemical reactors. It is also used for providing the elevated temperatures required for the operation of the resistive methane sensors.