Effect of spatial localization of dopant atoms on the spacing of electron subbands in dgr;hyphen;doped GaAs:Si

摘要

Using Raman spectroscopy we have investigated the spacing of the electron subbands in nominally dgr;hyphen;doped GaAs structures which show a considerable spread of the silicon dopant atoms along the growth direction. For optical excitation in resonance with theE0+Dgr;0band gap, spinhyphen;density intersubband excitations are observed. For excitation in resonance with theE1band gap we find a strong enhancement of scattering by collective intersubband plasmonhyphen;phonon modes. The measured energy spacings between the electron subbands deviate significantly from what is expected for ideal dgr; doping. Selfhyphen;consistent electronic subband calculations taking into account the spread of the dopant atoms along the growth direction, in contrast, yield a good quantitative agreement between calculated and measured subband spacings. This demonstrates the potential of intersubband Raman spectroscopy for the analysis of the spatial localization of dopant atoms in dgr;hyphen;doped structures.