Absence of magneto-intersubband scattering in n-type HgTe quantum wells

Magneto-intersubband scattering (MIS), which is a general feature in III-V semiconductor heterostructures with two occupied subbands, is demonstrated to be absent in both asymmetric and symmetric type-III HgTe quantum wells (QW’s). The analysis of the temperature dependence of Shubnikov–de Haas (SdH) oscillations and their fast Fourier transforms, together with the excellent agreement between the measured longitudinal resistivity and the calculated oscillations in the density of states in a magnetic field within the framework of an $8\times 8$ $\mathbf{k}\cdot \mathbf{p}$ model, completely rule out the MIS effect. The absence of the MIS effect in HgTe QW’s is ascribed to a much more complex and irregular Landau level alignment which suppresses the intersubband scattering rate. A natural consequence of the absence of MIS is that the Rashba spin splitting can be properly identified from the SdH oscillations in a perpendicular magnetic field and at a constant temperature, in contrast to the recent findings for InAs QW’s.