Micromachined structures of single-crystal silicon have been fabricate
d with a view to developing them for a number of potential uses. The s
tructures which are fabricated in (111) orientation silicon are undope
d thus permitting the incorporation of active circuit elements in the
structures themselves, Moreover no high temperatures, applied voltages
or long etch times are used in the fabrication sequence, thereby simp
lifying the task of integration with circuit processes. The potential
uses of these structures include photodiodes with high speed and effic
iency, accelerometers, or structures for stress or thermal isolation.