Influence of the Al concentration on the electronic properties of coupled and uncoupled AlxGa1−xAs/AlAs/AlyGa1−yAs double quantum wells

• Effect of different Al concentration on the electronic properties of coupled and uncoupled double quantum wells.
• Shubnikov-de Haas, Hall measurements and fast Fourier transform method were used.
• Electronic properties decrease, increasing Al content within the quantum wells.
• Alloy scattering effect explains decreasing of the electronic properties.

Shubnikov-de Haas (SdH) and Hall measurements have been used to investigate the electron densities and mobilities in a pair of adjacent two-dimensional electron gases (2DEGs), which were confined in coupled and uncoupled AlxGa1−xAs/AlAs/AlyGa1−yAs double quantum wells (DQWs), as a function of front-gate voltage (Vg). The electron densities and mobilities of the first and second sub-bands were determined using the fast Fourier transform (FFT) in both coupled and uncoupled samples, named S1, S2 and S3, which have different aluminum (Al) content in each well. Sample S1 was illuminated in order to reach the coupled behavior. The electronic properties of the samples have been compared, showing that the electron density and mobility decrease with increasing Al content within the quantum wells (QWs). The last fact was attributed to the alloy scattering in the AlxGa1−xAs quantum well.