OPTO-ELECTRO-MECHANICAL DEVICE OR FILTER, PROCESS FOR MAKING, AND SENSORS MADE THEREFROM

摘要

This invention relates to devices and their applications which employ a resonant semiconductor member whose vibratory motion is coupled to the radiant energy cast onto a photovoltaic energy conversion device. It also relates to such devices whose vibratory behaviour is otherwise affected and which affect can be read optically. Optical methods are used to drive the microbeam, sense the microbeam vibrations and, if certain conditions are met, produce self-oscillation with no intervening electro-optical components, thus eliminating the need for piezoresistors, drive electrodes, electrical contacts and any metallurgy for electrical interconnection. A resonant microstructure member of one electrical type (p or n) is formed over a wafer, this member extending substantially or fully over a cavity or other space in the wafer. At a location in a wall or floor of the cavity is a region of opposite type (p or n) material. The interface between the two types is a p-n junction and is the best known form of a photovoltaic structure. The flexible member and the opposite type region should be substantially in the path of the driving radiant energy. The devices of this invention act as opto-electro-mechanically coupled photodiodes-causing the flexible member to be attracted electrostatically to the opposite type region by the incident driving light. The close proximity of the flexible member to the substrate or to an integrated cover or top cap forms a Fabry-Perot interferometer capable of producing large intensity modulations of the reflected light with small displacements of the member. A preferred form would have the vibratory member located within an evacuated capsule. The top cap would seal the member off on one side, and the wafer on which it was mounted or formed would seal the other. Applications as pressure sensor, accelerometer, acoustic ranger apparatus and temperature sensitive apparatus.