| Group III nitride wide bandgap semiconductors have recently attracted considerable interest due to their applications for optical devices operating in the blue and ultraviolet (UV) wavelength regions. These materials were also found to be suitable for operation at high power levels, high temperatures and harsh environments. Some applications of UV photodetectors include chemical and biological analysis, flame detection, and optical communications. This project is based on designing AlGaN based quantum well UV photodetector. It has been determined that the presence of multiple quantum wells in the active region improves the device responsivity. The device performance depends on many factors that have been addressed in the design. One very important issue is the technological quality of the contacts used. The responsivity of the device is higher with lower specific contact resistivities. Part of this work addresses the deposition of Ti/Al ohmic contacts on n-type GaN. The Rectangular Transmission Line Model and Circular Transmission Line Model test patterns were used for measuring the specific contact resistivity and the results will be discussed. |
