Automatic Measurement of Spectra of a Tunnel Current

V.N. Vyukhin (Russia)


Tunnel junction, volt-ampere characteristic, small nonlinearity, tunnel current, derivatives of the current, noise, Δ-σ ADC


An instrument intended for measuring small nonlinearities of the volt–ampere characteristics of tunneling junctions at helium temperatures is described. The instrument contains a controlled scan unit and four 24-bit channels for measuring the current, the real and imaginary components of the first derivative of the volt–ampere characteristic (the conductivity), and the second derivate. On a scale 100 нА the derivatives sensitivity of the instruments is 0.4 pA and the dynamic range in measuring the current is 105 dB. Physically, the instrument is a single unit with an interface to the computer USB port.

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