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 4.5×10¹³ cm^-3. The dark current is significantly reduced by using a wider-band-gap material of quaternary In_xGa_1-xAs_yP_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 4.2×10^-7 A/cm².