Two-parameter Process Research Articles

1/f noise as a two-parameter stochastic process

In this paper the power spectrum of the «filicker 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. 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 expression of 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 energiesE1 andE2. 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 widthsx of the potential barrier are uniformly distributed between given limitsx1 andx2. The present model improves the single-parameter models discussed in the literature since it accounts for the characteristics of the trapping process and removes the discrepancies involved in the preceding descriptions. Numerical calculations for different sets of values of the model parameters are also given.