Development of novel photodiodes as a photon counter

Superlattice type photodiodes of a GaAs-Al/sub x/Ga/sub 1-x/As structure were studied at room temperature. A combination of potential-well width and barrier width was sensitive to the charge multiplication factor. Using a diode with a 10 nm well and a 15 nm barrier, the detector characteristics were investigated from a point of view of achieving a high gain. This type of photodiode was confirmed to be sensitive to Cherenkov light generated in water. Effects of carrier doping up to 10/sup 18/ cm/sup -3/ at room temperature on the multiplication rate is discussed.