LOW DEFECT DENSITY GaN PHOTODIODE

GaN-based p-i-n photodiodes are in ideal choice for the Air Force's UV radiation measurements needs since these solid-state detectors are compact, light, and have low power consumption. However, current GaN photodiodes have much larger dark currents than expected. This Phase I program seeks to dramatically improve the current state of GaN photodiodes by employing low dislocation density epitaxial lateral overgrowth (ELO) substrates. The ELO substrates will be produced by hydride vapor phase epitaxy which provides a growth rate approximately 50 times faster than conventional growth techniques and will enable uniformly low dislocation density over large areas. High quality p-i-n diodes will be fabricated on the ELO substrates and on sapphire to detemine the effect of dislocation density of detector performance. In Phase II, we will optimize the structure for increased responsivity and response time, shift the wavelength cutoff to shorter wavelengths by using AlGaN, and identify a commercial partner to package the detectors for high-volume sale of UV detectos.