SILICON AVALANCHE PHOTODIODE

There is provided an n+-p- pi -p+ APD having a shallow and abrupt p-n junction located about 1 to 2 mu m into the APD and having a p-type conductivity region containing acceptors in an uncompensated excess concentration corresponding to a dose of between about 5 and 10x1011 acceptors/cm2. The combination of the shallow p-n junction and the doping profile in the p-type concentration region gives rise to an electric field profile having multiplication spread substantially throughout the entire thickness of the central active region of the APD and having no drift region. The electric field profile peaks adjacent the p-n junction in a value of about 2.9x105 volts/cm. The electric field profile diminishes over the distance that the p-type conductivity region extends into the APD but remains at about 1.6x105 volts/cm to maintain multiplication throughout the thickness of the active region of the APD. The thickness of the APD and the multiplication region extending through the APD can be achieved with an acceptable increase in operating voltage provided that the APD has a thickness less than about 40 mu m.