10-Gbps InAlAs/InGaAs superlattice avalanche photodiodes

In this paper we report a method of dark current reduction in InAlAs/InGaAs superlattice avalanche photodiodes (SL-APDs). We have fabricated a mesa-ty pe SL-APD for 10-Gbps application. Two sets: of samples were fabricated usi ng benzocyclobutene (BCB) and SiNx passivations, and the dark current chara cteristics were compared. Extracting the surface dark currents for the two samples, we obtained the surface dark current of 6.3 nA for the BCB-passiva ted sample and 0.3 muA for the SiNx-passivated sample. The measured 3-dB ha ndwidth of the 30-mum mesa APD was 8.3 GHz.