Photon counting 1060-nm hybrid photomultiplier with high quantum efficiency

An ultra-low-noise, high-speed, hybrid photomultiplier tube sensitive from 900 to 1300 nm optical wavelength is described. The device, also known as an intensified photodiode (IPD), uses an active transferred electron (TE) photocathode with the quaternary In/sub .69/Ca/sub .31/As/sub .67/P/sub .33/ photo-absorbing layer and a GaAs Schottky avalanche photodiode (SAPD) anode. The detector has a combined electron bombarded and avalanche gain of over 15000 which is sufficient to overcome preamplifier noise and provide high internal counting efficiency of approximately 85%. At an active cathode bias of 1.5 V the room temperature cathode dark count rate is 6.67/spl times/10/sup 5//s. Cooling reduces this substantially corresponding to a dark current activation energy almost equal to the bandgap of the In/sub .69/Ca/sub .31/As/sub .67/P/sub .33/ layer.