MOS-transistor heater

Fig.4.17. Cross-section of a microhotplate with integrated MOS-transistor heater, D and S denote drain and soiu ce of the transistor...

The third microhotplate design included a MOS-transistor heater embedded in a silicon island (Sect. 4.4). One advantage of this configuration is the reduction of the... 

S. Muller. CMOS-Micro-Hotplate with MOS Transistor Heater for Integrated Metal Oxide Gas Sensors, Diploma thesis, ETH Zurich, Switzerland (2002). 

If the capacitor module (the capacitor and heater) is thermally isolated from the rest of the active device, the sensitivity can be increased. If the module is built on a cantilever, the thermal isolation can be enhanced. The thermal isolation of the heater element from the rest of the active device can be tested by measuring the MOS transistor current-voltage characteristics and the threshold voltage, with and without power to the heater element. The smaller the difference, the better the thermal isolation. 

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