The upper frequency limit of the 1tf noise and the surface relaxation time

Tests on etched reverse biased silicon diodes show that the time constant, τm, of the transition frequency between the 1tf- and the 1tf2-spectrum of the short-circuit noise current is of the order of 10−4 sec. Small charge variations of the surface states which were artificially generated by a small instantaneous change of the reverse current return to the equilibrium state with a relaxation time τ0 of 10−7 sec. The difference of approximately three orders of magnitude between the two time constants is unaffected by cooling of the diodes down to 77°K or by changing the surface ambient. The application of several models of 1tf-noise upon these results is discussed.