A high voltage solar cell array as an electrostatic MEMS power supply

A high voltage hydrogenated amorphous silicon (a-Si:H) solar cell array which is optimized as a power source for electrostatic microelectromechanical systems (MEMS) is presented. A single test cell consists of a triple stack of p-i-n/p-i-n/p-i-n material and produces open circuit voltage (OCV) of 1.8~2.3 volts, short circuit current density (J_sc) of 2.8 mA/cm², and fill factor (FF) of 0.495. A series interconnected array of 100 of these cells (total array area of 1 cm²) has been produced in an integrated fashion and produces an array OCV of 150 volts, and short circuit current (I_SC) of 2.8 μA under Air Mass (AM) 1.5 illumination. To illustrate the use of this array as a MEMS power source, it has been packaged with a movable micromachined silicon (Si) mirror in a hybrid manner. The movable Si mirror is directly driven by the cell array electrical output, and the motion of the mirror plate has been observed reproducibly. Variation of light intensity and/or number of illuminated cells produces different array OCVs, thus enabling control of the deflection of the Si mirror by variation of incident light