Structure in the flicker-noise power spectrum of n-InSb

We have measured the power spectrum of flicker noise in high-purity, single-crystal n-InSb at 76 K in the frequency range 0.1 Hz-10 kHz. The power spectrum can be interpreted as a superposition of two noise spectra. One of them is 1/f like at frequencies above a cutoff frequency f₀ which is on the order of a few hundred Hz, while at frequencies below f₀ it appears to level off to a constant value. The second spectrum is dominant at frequencies well below f₀ and behaves as 1/f. Noise power much smaller than that predicted by the Hooge relation, S_δV=αV²/NF, is observed. Also it is found that chemical treatments of the surface have a strong influence on the magnitude of the measured flicker noise.