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

Abstract

A hydrogenated amorphous silicon (a-Si:H) solar cell array that is designed as an on-board power source for electrostatic microelectromechanical systems (MEMS) is presented. A single cell consists of a triple layer of p-i-n/p-i-n/p-i-n a-Si:H and produces an open circuit voltage (V/sub OC/) of 1.8/spl sim/2.3 V, a short circuit current density (J/sub SC/) of 2.8 mA/cm/sup 2/, and fill factor (FF) of 0.495. A series interconnected array of 100 single solar cells (total array area of 1 cm/sup 2/) is fabricated in an integrated fashion and produces an array V/sub OC/ of 150 V, and array short circuit current (I/sub SC/) of 2.8 /spl mu/A under Air Mass (AM) 1.5 illumination. To demonstrate the usefulness of this solar cell array as an on-board power source for electrostatically driven micromachined devices, 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 values of array V/sub OC/, thus enabling control of the deflection of the Si mirror by variation of incident light intensity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>