Temperature dependence of the gate-controlled portion of ion-controlled diodes

The ion-controlled diode is a gate-controlled diode where the gate is replaced by an ionic conducting solution and the insulator is composed of the usual oxide, a barrier against diffusion, and a chemically sensitive membrane with reasonably specific sensitivity to a given ion. In order to establish the utility of this structure for a down-hole sensor in geothermal brine wells, a series of experiments were conducted with a standard gate-controlled diode to confirm calculations on the temperature dependence of the response. Excellent agreement was obtained including a negative phase shift in the measured admittance at elevated temperatures. The degree of agreement gives us confidence that it will be possible io eventually construct a 250°C sensor.