III-V membrane structures for tunable Fabry-Perot filters and sensor applications

The introduction of III-V semiconductor technology in the field of micromechanics allowed the development of novel electronic and optoelectronic devices, in particular comprising actuator and sensor applications. In this work we report on InP-based micromachined Fabry-Perot microcavity structures for use as tunable optical filter application in telecommunication systems operating in the 1.55 μm wavelength regime. Various approaches for the filter realization are discussed in terms of their technological constraints. Presented here are the results of bulk micromachined Fabry-Perot filters including thermal and electrostatic actuation principles for wavelength tuning. The moving mirror of the filter is implemented in the form of suspended semiconductor thin membrane structures. The influence of intrinsic mechanical stress in the membrane layers as well as actuation induced stress has been characterized in order to optimize the optical filter performance. Compound semiconductor micromachining technology enables the realization of mechanical and thermal sensor systems showing excellent and formerly not achievable performance. As an example we focused on a resonant-tunneling-diode (RTD) based concept for very sensitive stress and pressure sensing applications