Contact characterization and persistent photoconductivity effects in MBE grown n-type gallium nitride

Gallium nitride is a wide bandgap semiconductor, with a bandgap energy of 3.4eV, which can be used to make blue and ultraviolet optoelectronic devices. Globally, research focuses on the growth of good quality materials. Dr. Thomas Myers, from the Physics department at West Virginia University, has grown GaN on sapphire substrates by atomic hydrogen assisted Molecular Beam Epitaxy. This research addresses the fabrication and characterization of metal contacts to these unintentionally doped n-type MBE grown GaN samples. Also, temperature dependent and spectral dependent persistent photoconductivity measurements were taken. Gold was evaporated forming Schottky contacts and aluminum was sputtered forming ohmic contacts using a circle and ring structure by the liftoff process. I-V and C-V curves were measured producing a majority carrier concentration of 7.5*1017cm-3. Resistivities of 0.262Ocm were measured using the Van der Pauw technique. Temperature dependent PPC measurements suggest a DX center exists with an activation energy of 95meV.