ADMITTANCE SPECTROSCOPY STUDIES OF BORON DELTA-DOPED SI QUANTUM-WELLS

The admittance spectroscopy technique has been used to study the hole confinement in boron delta-doped Si quantum wells. Based on the carrie r thermal emission model, the activation energies of holes confined in the quantum wells are obtained from the measured conductance spectra. For different well widths, i.e., different boron doping amounts, the well depths and the subband positions are different. We observe the sh ifts of the conductance peaks in the spectra for delta-doped samples w ith the peak doping concentration of 2 X 10(20) cm(-3) and doped thick nesses of 1.2, 3.0, and 5.0 nm. The activation energies derived from t he measurements are 0.11, 0.30, and 0.34 eV, respectively. A self-cons istent calculation of the subbands in the quantum wells verifies that these activation processes correspond to the hole emissions from the h ole ground states in the delta-doped quantum wells to the Si valence b and.