1/f noise as a two-parameter stochastic process

The power spectrum of the 'flicker noise', produced by the fluctuations of the electrical conductivity in semiconductors, thin discontinuous metal films, etc., is calculated by means of a two-parameter model. The calculations take into account that the electrical conductivity is modulated by a trapping process, using the vacancy time and the trap occupancy time as stochastic variables. By means of Machlup's (1954) expression for the power spectrum of a two-parameter process, a new power spectrum formula is obtained under the assumption that the traps have a constant distribution law between limiting energies. The same formula for the noise power spectrum holds even if traps have a definite energy, but access of electrons is by tunnelling, and the widths of the potential barrier are uniformly distributed between given limits.