  The master-equation approach provides generation-recombination (g-r) noise in
bulk semiconductors in terms of parameters of conduction electrons. It is shown
that the g-r bulk noise can also be described by the random succession of
elementary g-r pulses. This enables g-r bulk noise to be interpreted in terms
of the numbers of traps. The transition from g-r bulk noise to discrete
switching in small-area semiconductors is found by reducing the number of traps
to just one single active trap. The resulting g-r noise spectrum is shown to be
equivalent to Machlups noise spectrum. The probability of an overlap of
succeeding g-r pulses is calculated. Such an overlap is attributed to the
occupation of an empty single trap by an electron transferred from a
neighboring trap. Simulating a g-r pulse train we find a large variety of
patterns similar to those observed in MOSFETs. Excluding overlapping g-r
pulses, the up and down distribution of succeeding g-r pulses is estimated.
