Characterization of δ-doped silicon by electrolyte electroreflectance

In a commercial MBE system δ-doped silicon layers are prepared followed by epitaxial growth of undoped cap layers. For the characterization of these structures the electrolyte electroreflectance technique is used in connection with successive layer removal by anodic oxidation. The measurements are carried out in the range of the complicated 3.4 eV structure. In the high-energy region of the electroreflectance spectra the lineshape is independent of electric field and the amplitude of the 3.46 eV peak follows the derived dependences on dc bias, modulation voltage, and cap layer thickness. It is shown that this peak is a suitable optical probe to localize the δ-layer and to determine its areal doping density.