Three Guises of Generation-Recombination Noise

摘要

It is shown that the noise in a zero-biased junction may be just a manifestation of the normally-occurring generation-recombination process, rather than shot noise, as is usually presumed. In addition, an attempt is made to clarify some noise mechanisms in semiconductors by addressing mathematical interpretation and terminology. In particular, for a biased homogeneous material at low frequencies, where the relevant transport mechanism is drift, a shot-like expression of the g-r noise equation is derived. For a zero-biased junction at low frequencies, where the relevant transport mechanism is diffusion, a pure shot-like expression of the g-r noise equation and an equivalent thermal (Nyquist) expression is derived. In both the homogeneous and the junction cases, however, the true noise remains generation-recombination noise, i.e., the origin of the noise is the fluctuations in the rates of generation and recombination of free carriers.