The silicon PIN photodiode is an important part of the PbWO4 detector read-out system that will be used in the Photon Spectrometer (PHOS) in the CERN/ALICE experiment. High specific resistivity n-type silicon material is used for the first time in our R&D of PIN

and special techniques are employed in the production process to ensure low dark current

high quantum efficiency

and low noise. The PIN diode has a sensitive area of 16 mm×17 mm. The leak current is lower than 5 nA at room temperature

the quantum efficiency in the wavelength range of 400—500 nm is about 82%

and the junction capacity is about 110—120 pF. The noise level (ENC) of PIN+PreAmp system is lower than 600 e at –25℃. The PIN diodes have passed the long-term stability test. The performance of our R&D PIN photo-diodes has overall met the ALICE/PHOS requirement.