| Gallium Nitride and its associated alloys InGaN and AlGaN have many material properties that are highly desirable for micro-electro-mechanical systems (MEMS), and more specifically micro-opto-electro-mechanical systems (MOEMS). The group III-nitrides are tough, stiff, optically transparent, direct bandgap, chemically inert, highly piezoelectric, and capable of functioning at high temperatures. There is currently no other semiconductor system that possesses all of these properties. Taken together, these attributes make the nitrides prime candidates not only for creating new versions of existing device structures, but also for creating entirely unique devices which combine these properties in novel ways.; Unfortunately, their chemical resiliency also makes the group III-nitrides extraordinarily difficult to shape into devices. In particular, until this research, no undercut etch technology existed that could controllably separate a selected part of a MEMS device from its sapphire or silicon carbide substrate. This has effectively prevented GaN-based MEMS from being developed.; This dissertation describes how this fabrication obstacle was overcome by a novel etching geometry (bandgap-selective backside-illuminated photoelectochemical (BS-BIPEC) etching) and its resulting morphologies. Several gallium-nitride based MEMS devices were created, actuated, and modelled, including cantilevers and membranes. We describe in particular our pursuit of one of the many novel device elements that is possible only in this material system: a transducer that uses an externally applied strain to dynamically change the optical transition energy of a quantum well.; While the device objective of a dynamically tunable quantum well was not achieved, we have demonstrated sufficient progress to believe that such a device will be possible soon. We have observed a shift (5.5meV) of quantum well transition energies in released structures, and we have created structures that can apply large biaxial stresses, which are required to produce significantly larger tuning (up to several hundred meV) in quantum well-based devices. |
