A device physics model is developed to analyze spontaneous neuron‐like spike train generation in current driven siliconp+‐n‐n+devices in cryogenic environments. The model is shown to explain the very high dynamic range (107) current‐to‐frequency conversion and experimental features of the spike train frequency as a function of input current. The devices are interesting components for implementation of parallel asynchronous processing adjacent to cryogenically cooled focal planes because of their extremely low current and power requirements, their electronic simplicity, and their pulse coding capability, and could be used to form the hardware basis for neural networks which employ biologically plausible means of information coding.