Uniformity in the electrical characteristics of GaAs/AlAs tunnel structures grown by metalorganic chemical vapor deposition

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Abstract
Uniformity of current-voltage characteristics in GaAs/AlAs tunnel structures grown by metalorganic chemical vapor deposition has been investigated by studying electronic transport perpendicular to GaAs layers separated by one or two AlAs barriers. For each sample, measurements of the current-voltage curves and their first and second derivatives, for series of 10 to 80 identical devices taken randomly across the sample, gave reproducible and uniform results. These showed evidence that the doping concentrations and layer thicknesses were uniform across the wafers. In single barrier structures, they further suggested that the average fluctuations in the thicknesses of ultrathin layers should be within one atomic layer.