InAs n-i-p Diodes Fabricated Using S and Si Ion Implantation

Planar indium arsenide (InAs) electron avalanche photodiodes (e-APDs) can provide significant avalanche gain with negligible excess noise. Reported InAs e-APDs are so far all top-side illuminated p-i-n diodes. Yet, back-side illuminated n-i-p diodes are needed to be compatible with focal plane arrays (FPAs) (bump-bonding process). This work reports n-type ion implantation into i-InAs layer grown on p-InAs layers, forming n-i-p diodes for the first time. Electrical and optical characteristics of S- and Si-implanted mesa and planar photodiodes are investigated both experimentally and through simulation. The mesa InAs n-i-p diodes fabricated from implanted samples exhibit similar dark current densities to previously reported Be implanted mesa InAs p-i-n diodes. A peak responsivity of 1.09 A/W at 2004 nm wavelength was demonstrated using S implanted detectors after rapid thermal annealing at $600~^{\circ }$ C for 30 s. The simple planar diodes exhibit higher dark current compared to Be implanted planar InAs p-i-n diodes. This is attributed to poor junction isolation resulting from n-type unintentional doping in intrinsic InAs layers. This can be mitigated by adding isolation trenches around the diodes or introducing p-type isolation implant. Therefore, we have demonstrated a promising approach for fabricating bump-bonding compatible and back-illuminated InAs n-i-p planar diodes.