Abstract
This study reports a novel micro electrostatic vertical comb-drive actuator (VCA) driven by the photovoltaic effect that results from incident light. The vertical comb electrodes have a pn junction structure. The VCA with pn-combs can be driven by the photovoltaic effect. The combination of the photovoltaic effect and reverse bias can further increase the driving amplitude of the VCA. To demonstrate the feasibility of the proposed concept, the VCA with pn-combs was fabricated on an epitaxial silicon wafer and successfully driven resonantly by intensity-modulated laser light. The first torsional mode of a typical fabricated VCA is at 1.46 kHz. Moreover, the VCA driven using (1) optical driving, and (2) optical driving with DC reverse bias, were also demonstrated. This study also demonstrates the 2-axis epitaxial silicon scanner driven by the coil-less magnetostatic force using electroplated permanent magnet film. The present approach has four merits: (1) the process employs the cheap silicon wafer with epitaxial layer; and the electrochemical etching stop technique is used to precisely control the thickness of scanner; (2) the I-section rib-reinforced structure is implemented to provide high stiffness of the mirror plate; (3) the magnetostatic driving force on scanner is increased by electroplated permanent magnet film with slender patterns; (4) the size of packaged scanner is reduced since the assembled permanent magnets are not required.