Current Fluctuations in Single Barrier Vertical GaAs/AlAs/GaAs Tunneling Devices

Abstract

We report the experimental results of the low temperature (T = 4.2 K) low-frequency current fluctuations measurements in the single-barrier resonant tunneling GaAs/AlAs/GaAs device with Si δ-doping in the center of the 10 nm thick AlAs barrier. The dimensions of the device were 200 µm by 200 µm. For the biasing voltages 0.1 V < |U | < 1 V we observed the Fano factors between F = 0.7 and F = 0.95. We explain it by the existence of the trapping centers/imperfections/resonant levels inside the barrier participating in the transport for this range of voltages. Only for the smallest biasing voltages the Fano factor tends to F = 1, expected for a highly nontransparent barrier.

Transport in GaAs/AlAs/GaAs [111] Tunnel Junctions

“…However, at biases higher than 0.6 V, the generation-recombination noise appears in the low frequency part of the spectrum, which indicates that some electron traps (e.g. donor states) are active in the tunneling process [6,7]. More quantitative results come from the analysis proposed in [9] (subtracting the shot noise value and then dividing by a square of current for a given bias), which visualize the relative modulation noise spectral density.…”

“…Circular junctions with diameters of 125, 250 and 500 µm were prepared by optical lithography. Two kinds of transport measurements were performed: (1) current-voltage characteristics, where a DC bias was applied between the top contact and bottom electrode and tunneling current was measured, and (2) current noise spectral density, where the fluctuations of tunneling current for a fixed bias were measured by means of cross-correlation technique [6,7]. All the measurements were made at 4 K.…”

Observation of Thermally-Activated Electron Traps in GaAs/AlAs/GaAs Heterostructures in Low-Frequency Noise Measurements

“…The current noise has been measured by means of cross-correlation method with two independent transimpedance home-made amplifiers with gain 10 7 and 10 8 V/A [3,4]. Analysis of the current data has been performed in Matlab • R .…”