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HL: Fachverband Halbleiterphysik

HL 33: Nitrides: Devices

HL 33.6: Vortrag

Mittwoch, 19. März 2025, 12:30–12:45, H15

Characterisation of a Pt on-chip counter electrode on a GaN/AlGaN-ISFET Wheatstone bridge as pH-sensor — •Alexander Hinz¹, Niklas Krantz¹, Stephan Figge¹, and Martin Eickhoff^1,2 — ¹Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany — ²MAPEX Center for Materials and Processes, University of Bremen, Bibliotheksstraße 1, 28359 Bremen, Germany

The influence of a Pt on-chip counter electrode on field effect transistors as pH-sensors was investigated. The intention was to reduce the size of the complete sensor structure consisting of ISFET, counter and reference electrode. In addition, the function of the Pt on-chip electrode was be compared to setup using an external Pt counter electrode to discuss stability and leakage. Furthermore, a Wheatstone bridge design is used to compensate temperature drifts. A reduction of this drift to 0.02 mV/°C was achieved. The long-time behavior of the temperature drift and also of pH changes was also analysed.

Keywords: ISFET; pH sensor; GaN