MODULATION OF CARRIER DISTRIBUTIONS IN DELTA-DOPED QUANTUM-WELLS

We present the modulation effect of carrier distributions in delta-doped quantum wells (QWs). For identical Si or Be dopant distributions, the carrier distributions are significantly affected by the confinement of QWs having different thicknesses. For both types of carrier we find a QW thickness for maximum confinement, with thicker or thinner wells resulting in less confinement. An extremely narrow capacitance-voltage profile with a full width at half maximum of 5 angstrom is observed in Be delta-doped AlGaAs/GaAs QWs of width 50 angstrom. The sheet conductivities determined from Hall measurements also exhibit strong dependence on the spatial distribution of carriers. The modulation effects are mainly governed by the subband energy levels and the spatial extent of the carrier wave functions. Photoluminescence spectra reflect the rise of the Fermi energy caused by enhanced confinement of carriers by QWs.