New methods for the characterization of surface states density and substrate/epilayer interface states in pseudomorphic AlGaAs/InGaAs/GaAs heterostructures

Temperature-dependent charge-carrier transport between Si-δ-doped layers and AlGaAs/InGaAs/AlGaAs quantum well with various space layer thicknesses measured by Hall-effect analysis

“…Simplified band diagrams modelling by two back-to-back capacitors. Unlike homogeneous bulkdoped materials, where the electrons and ionized donors appear in the same spatial location, for Si-δ-doped heterojunction QW the electrons are transferred to the QW region while the ionized donors remain in the δ-doped layers [11][12][13][14][15][16][17][18][19] . Because of the separation of charges, a model consisted of two back-to-back capacitors was chosen to calculate the internal transverse electric field (F) and electric potential difference ΔV across the space layer.…”

“…In contrast to the homogeneous bulk-doped structure [7][8][9] , the uniform modulation doping in barrier layers of III-V QW structure can supply charge carriers in the undoped active channel with high mobility due to less scattering from ionized dopants 10 . Furthermore, the single Si-δ-doping (modulation doping with single Si-doping plane) [11][12][13][14][15][16] in the barrier layer with appropriate space layer thickness (t S ) can offer effectively more 2DEG than the uniform modulation doping. As compared to the single Si-δ-doping, the dual and symmetric Si-δ-doping (modulation doping with two planes of Si evenly separating into two sides of the active channel with appropriate t S , see Fig.…”