GaInNAsSb/GaAs Photodiodes for Long-Wavelength Applications

GaInNAsSb p-i-n photodetectors on GaAs substrates capable of detecting wavelengths up to 1550 nm with a reduced dark current are presented in this letter. Responsivities of 0.18 A/W at 1300 nm and 0.098 A/W at 1550 nm were achieved in devices with a ~0.5-μm-thick GaInNAsSb p-i-n epitaxial layer with 10% In, 4.08% N, and 4.4% Sb. The absorption coefficient (α) spectra show that α is intrinsically higher than that of the indirect-gap Ge layer but ~2.6 times lower than that reported for a In
_0.53
Ga
_0.47
As epitaxial layer at 1550 nm. The dark currents of the GaInNAsSb devices are found to be lower than not only those of the GaInNAs devices of a similar energy gap but also the state-of-the-art Ge/Si avalanche photodiodes. The lower dark currents in the GaInNAsSb devices compared with the GaInNAs devices can possibly be attributed to the reduction of defects in the Sb-containing epitaxial layer.