Magnetocapacitance and far-infrared photoconductivity in GaSb/InAs composite quantum wells

Magnetocapacitance-voltage measurements are performed in hybridized composite quantum wells at 4.2 K. In the quantum Hall regime, the capacitance reveals a series of oscillations resulting from the spin-resolved Landau levels. It is found that the capacitance signal is determined by the filling factor that is the difference between the electron and hole filling factors. A fan chart is generated in order to determine the Fermi level position relative to the electron and hole subbands at different gate voltages. When the Fermi level resides in the middle of the hybridization gap, far infrared photo signals have been detected with photon energy ranging from 1.4 to 5.3 meV. The hybridization gap is determined to be 3 meV.