A thermal-induced electric current from a gold electrode/porous silicon device

Abstract

We demonstrate the electric current measured from a device composed of electrochemically etched silicon, porous silicon (PS) and gold (Au) electrodes of different device designs by applying a thermal potential between two Au electrodes. Compared to conventional PS of high contact resistance between Au/PS due to the homogeneously dispersed nanopores, our PS inhibits the discontinuous, island-shaped and micro-sized Si structures, which decrease the Au/PS contact resistance. When one Au electrode is heated, a temperature gradient (ΔT) is generated between the two electrodes and the electric current can be directly measured by a current meter under a close circuit condition. The output current not only depends on the electrode design but also on the distance between the electrodes. For the comb-shape electrode with finger lengths of 8 mm, widths of 0.1 mm, and finger separation of 0.14 mm, using a 25 °C setting temperature (T_set) can generate ΔT = 0.4 K, which corresponds to 14.2 μA. For the Au/PS device with two 16 mm² square electrodes separated by a 2 mm distance, the current increases with increasing T_set and reaches a maximum value of 25 μA corresponding to ΔT = 3.4 K. Our Au/PS device has potential in sensitive temperature sensors operated at temperatures lower than 60 °C.