Lateral epitaxial overgrowth of GaN on sapphire and silicon substrates for ultraviolet photodetector applications

Lateral epitaxial overgrowth of GaN thin films was conducted by low-pressure metalorganic chemical vapor deposition on basal plane sapphire and (111) silicon substrates. The films were characterized through X-ray diffraction, photoluminescence, scanning electron microscopy, atomic force microscopy and deep level transient spectroscopy. Schottky metal–semiconductor–metal ultraviolet photodetectors were fabricated on LEO grown GaN films for the first time. The spectral responsivity, its dependence on optical excitation power and bias voltage, and the device time decay properties were characterized. The orientation of the interdigitated fingers with respect to the LEO stripes was investigated.