1/f noise in InGaAs/GaAs linear graded buffer layers

Noise spectroscopy has been used as a sensitive technique to assess the quality of In_xGa_1-xAs linear graded buffer layers grown onto GaAs substrates. Samples having different dislocation structure and quality, determined by design and growth conditions, have been analyzed. Samples with a high dislocation density have been shown to be very efficient 1/f noise sources, with Hooge´s parameters (α_H) as high as 4×10^-1. A Hooge model, based on mobility fluctuation in the depletion regions surrounding dislocations, has been used to explain the observed dependence of α_H on mobility μ. While a power law α_H∝μ^β with β≈-1 is found for the noise generated in samples with a high dislocation density (HDD), β≈+2 seems to hold when sample quality improves, where much lower α_H values (100 times) are obtained. These results allow to correlate the scattering centers that limit the mobility with the noise sources existing in the conducting layer of these structures