Inverted InAlAs/InGaAs Avalanche Photodiode with Low–High–Low Electric Field Profile

We propose a new p-down inverted avalanche photodiode (APD) structure suitable for a scaled APD with smaller junctions. The inverted APD structure has an edge-field buffer layer to prevent undesirable edge breakdown and suppress the excess surface leakage current associated with the InGaAs mesa surface. The fabricated back-illuminated InAlAs/InGaAs APDs show excellent multiplication characteristics without edge breakdown. An f 3dB of 27 GHz and a GB product of 220 GHz are obtained for these APDs.