title: Using a floating-gate MOS transistor as a transducer in a MEMS gas sensing system.
abstract: Floating-gate MOS transistors have been widely used in diverse analog and digital applications. One of these is as a charge sensitive device in sensors for pH measurement in solutions or using gates with metals like Pd or Pt for hydrogen sensing. Efforts are being made to monolithically integrate sensors together with controlling and signal processing electronics using standard technologies. This can be achieved with the demonstrated compatibility between available CMOS technology and MEMS technology. In this paper an in-depth analysis is done regarding the reliability of floating-gate MOS transistors when charge produced by a chemical reaction between metallic oxide thin films with either reducing or oxidizing gases is present. These chemical reactions need temperatures around 200 °C or higher to take place, so thermal insulation of the sensing area must be assured for appropriate operation of the electronics at room temperature. The operation principle of the proposal here presented is confirmed by connecting the gate of a conventional MOS transistor in series with a Fe(2)O(3) layer. It is shown that an electrochemical potential is present on the ferrite layer when reacting with propane.
authors.affiliation: CINVESTAV-IPN, Electrical Engineering Department, Av IPN No 2508, Col San Pedro Zacatenco, Mexico, DF 07360, Mexico. mreyes@cinvestav.mx
authors.forename: Mario Alfredo Reyes
authors.initials: MA
authors.lastname: Barranca
authors.forename: Salvador
authors.initials: S
authors.lastname: Mendoza-Acevedo
authors.forename: Luis M
authors.initials: LM
authors.lastname: Flores-Nava
authors.forename: Alejandro
authors.initials: A
authors.lastname: Avila-García
authors.forename: E N
authors.initials: EN
authors.lastname: Vazquez-Acosta
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Moreno-Cadenas
authors.forename: Gaspar
authors.initials: G
authors.lastname: Casados-Cruz
mesh_terms: D005740:Gases / Q000032:analysis*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation* / Q000379:methods*; D014159:Transducers; D014173:Transistors, Electronic
chemical_list: D005740:Gases