Probing the effective mass anisotropy of $\Gamma$ electrons in a GaAs/(AlGa)As quantum well

We use resonant magnetotunneling spectroscopy to probe the band structure of the lowest-energy electron subband of a GaAs (001) quantum well, embedded in a resonant tunneling diode. A magnetic field, B, is applied perpendicular to the tunneling direction. The amplitude and bias position of the resonant peaks in the tunnel current are sensitive to both the magnitude and orientation of B relative to the crystalline axes. Consistent with earlier work, the axis of the anisotropy rotates by $90°$ on reversing the bias direction, as a result of interface band mixing. By incorporating a single atomic layer of InAs into the quantum well we can modify the eigenfunction of the lowest subband and hence control and investigate the nature of the band anisotropy.