A germanium diffused-junction photo-electric cell

The paper describes a new type of germanium-junction photo-electric cell, in which the junction is manufactured by impurity diffusion. This type of cell differs from those made by other methods in having a lower noise level and a slightly extended long-wave response. The possible causes of this latter anomaly are discussed, and some applications are suggested which utilize both effects. Two practical photocells are described which differ mainly in physical dimensions. Both are hermetically sealed and have high sensitivity and large output for their size. It is shown that the maximum reverse voltage that can be applied to a germanium junction device is a function of the cooling arrangements provided. The special case of the photocell is considered, and it is shown that the criterion for thermal stability is temperature rise rather than absolute temperature. For a germanium photocell in the dark the maximum temperature rise is approximately 11°C.