Abstract
In this work we present an hydrogenated amorphous silicon (aโSi:H) temperature sensor integrated in a thin film heater to perform biomolecular treatments. The system is fabricated on a microscope glass slide and includes a PolyDiMethylSiloxane (PDMS) chamber to confine the solution containing the sample and to avoid its evaporation. The heater is a 200โnmโthick titanium/tungsten sputtered film with a serpentine shaped geometry that has been designed by a finite element simulator in order to obtain a spatialโuniform temperature distribution. A uniformity better than 3% has been achieved over the surface of the structure. The temperature sensor is a nโtype/intrinsic/pโtype aโSi:H stacked structure deposited by plasma enhanced chemical vapor deposition. The top and bottom contacts of the diode are made by the same metal utilized to fabricate the heater. The characterization of the sensor response has been performed both under forward and reverse bias condition. In reverse bias condition, at fixed voltage, the currentโtemperature curve exhibits an exponential behavior. In forward bias condition, at constant bias current, the voltage across the diode is linearly dependent on the temperature in the range 30โ90โยฐC. In particular, using a constant bias current of 10 nA, a sensitivity around โ3.3โmV/ยฐC has been achieved.