Formation of guard ring of avalanche photodiode based on the InGaAs/InP heterostructure

The suppression of the early edge breakdown in planar avalanche photodiodes based on the InP/InGaAs heteroepitaxial structures is analyzed. A structure with a sunken central part and shallow periphery fabricated with the aid of wet chemical etching with the subsequent one-step diffusion of zinc is employed. The etching rates of epitaxial InP are determined for several etching agents. The composition of etching agent and the optimal etching regimes are determined. A p–n junction with the 0.5-μm-sunk central part and 1.3-μm-deep shallow periphery (guard ring) is obtained with the aid of wet chemical etching of the upper InP epitaxial layer in the acid mixture HCl: HNO3: H3PO4 and one-step diffusion of zinc. The proposed method makes it possible to avoid early edge breakdown in the avalanche photodiode based on the InP/InGaAs heterostructure, in particular, in the production of commercial avalanche photodiodes.