Low dark current InGaAs(P)/InP p-i-n photodiodes

Planar InGaAs(P)/InP p-i-n photodiodes have been successfully fabricated by an LP-MOCVD. High-quality and uniform epitaxial layers are obtained. The InGaAs layer background concentration is as low as 4.5/spl times/10/sup 13/ cm/sup -3/. The dark current is significantly reduced by using a wider-band-gap material of quaternary In/sub x/Ga/sub 1-x/As/sub y/P/sub 1-y/ as a cap layer to reduce the device surface leakage current. The p-i-n photodiode with a wide-band-gap InP cap layer exhibits a dark current as low as 60 pA at -10 V bias, corresponding to a dark current density of 4.2/spl times/10/sup -7/ A/cm/sup 2/.