Planar InP/InGaAsP three dimensional graded-junction avalanche photodiode.

A new planar InP/InGaAsP avalanche photodiode, which is fabricated by Be sup + implantation through a dishshaped InGaAs mask, has been developed. A three dimensional graded-junction is obtained and a uniform gain as high as 30 is achieved without edge or surface breakdown. The dish-shaped InGaAs implantation mask is formed by a photoelectrochemical etching technique. Device modeling indicates that the graded junction and low doping concentration can prevent edge breakdown and greatly suppress the surface field. The diode has a separated absorption and multiplication structure grown by hydride vapor phase epitaxy. These devices exhibit low primary dark currents (~ 10 nA), and high quantum efficiencies close to an InGaAs PIN at 1.3micron wavelength. Sensitivity measurements at bit rates of 1.7 Gbit/s give a minimum average receiver power required for 10 sup(- 9) BER of -35.5 dBm.