| The design and construction of transistors, even with advanced heterostructures, is limited by the lattice constants of the materials. High quality films of semiconductors with large lattice constants such as InGaAs cannot be grown directly on semiconductors with small lattice constants such as GaN. Direct wafer bonding allows the device designer to integrate materials that cannot be grown epitaxially. Integrating two materials such as InGaAs and GaN offers the potential for the construction of an 'ideal' transistor, with a high-mobility electron injector and highbreakdown electron collector.;The transport of current across the bonded interface is explored in this thesis, beginning with InP-GaN n-n diodes. These diodes showed rectifying behavior similar to that of a Schottky diode. InGaAs-GaN n-n diodes were constructed and also showed a rectifying behavior, with reduced current due to a less-favorable conduction band lineup. An InGaN interlayer was introduced to reduce the barrier to electrons passing through the bonded interface, and current increased for both InGaAs and InP.;The first bonded FET constructed was a lateral device that did not succeed in flowing current from source to drain, and was abandoned in favor of a vertical device, the Bonded-Aperture Vertical Electron Transistor (BAVET). Based on a similar non-bonded device (the CAVET), the BAVET consists of the InGaAs MESFET channel region sitting on top of a conductive aperture, thus draining vertically through the aperture. Initial attempts were unsuccessful as the isolation implant used to form the aperture choked off the current flow. By annealing the implanted GaN layer and regrowing InGaN instead, a functioning device was produced. The device, however, suffers from current leakage issues, primarily through the regrown InGaN around the gated InGaAs channel and does not fully pinch off.;Although a fully functioning device was not produced, this thesis demonstrates the viability and potential of the BAVET. There are numerous avenues available to improve and extends its performance, including a shallow InGaN implant, N-face GaN, and a InGaAs HEMT instead of the MESFET structure. |
