Low dark current p-i-n (Al,Ga)N-based solar-blind UV detectors on laterally epitaxially overgrown GaN

Abstract

Solar-blind ultraviolet photodiodes with a cutoff wavelength of 285 nm were fabricated on Laterally Epitaxially Overgrown (LEO) GaN grown by metalorganic chemical vapour deposition (MOCVD). Current-voltage measurements of the diodes exhibited dark current densities as low as 10 nA/cm/sup 2/ at -5 V. Spectral response measurements revealed peak responsivities of up to 0.05 A/W. For comparison, diodes were fabricated using the same p-i-n structure deposited on dislocated GaN. These diodes had dark current densities over seven orders of magnitude higher. In addition, whilst having comparable peak responsivities, the diodes on dislocated GaN had a less sharp cutoff.