A set-up for measurement of low frequency conductance fluctuation (noise) using digital signal processing techniques
Ghosh, Arindam · Kar, Swastik · Bid, Aveek · Raychaudhuri, A. K.
Original · EN
We describe a set up for measurements of low frequency (1 mHz < f < 20 Hz) conductance fluctuations in a solid conductor. The set-up uses a five probe a.c. measurement technique and extensive digital signal processing to reach a noise floor down to Sᵥ(f) ≤ 10⁻²⁰ V²Hz⁻¹. The set up also allows measurement of noise using an a.c. in presence of a superimposed direct current. This feature is desirable in studies of electromigration damage or in systems that show non-linear conductivity. In addition, we describe a scheme which allows us to obtain the probability density function of the conductance fluctuation after subtracting the extraneous noise contributions (background) from the observed noise. The set-up has been used for conductance fluctuation measurement in the temperature range 1.5 K < T < 500 K in the presence of magnetic fields. We present some representative data obtained by this system.
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