Magnetic depopulation of electronic subbands in low-dimensional semiconductor systems and their influence on the electrical resistivity and Hall effect

In many modern semiconductor devices transport is no longer three-dimensional because electrical confinement may split up the density of states such that several two-dimensional (2D) or one-dimensional (1D) subbands are occupied. A suitably orientated magnetic field causes depopulation (emptying) of higher subbands. This occurs because the magnetic field has two effects; firstly it diamagnetically increases the energy levels and separations and secondly, it increases the density of states. Calculations of these effects have been made using the WKB method for MESFET/JFET type devices (depopulation of 2D subbands) and for a model potential of a confined 2DEG (depopulation of 1D subbands). The authors outline the behaviour of the electrical resistance under such conditions and comment on the effect of such depopulation on the Hall effect (including the quantum Hall effect) as 1D subbands are depopulated.