Probing the Electronic Structure at the Heterovalent GaP/Si Interface using Electron Energy-Loss Spectroscopy

Accurate determination, with nanometer scale spatial resolution, of the semiconductor electronic structure information via valence electron energy-loss spectroscopy (VEELS) is discussed. Specifically, the use of reduced accelerating voltages, higher collection angles, and thinner specimens is investigated. This discussion is applied to the heteroepitaxial GaP/Si materials system to analyze potential electronic shifts near and away the heterovalent, lattice-mismatched interface. Results to date suggest that residual misfit strain in the GaP epilayer yields changes within in the material's dielectric function, while such changes are not observed in the bottom Si substrate. While this effort is still ongoing, such results imply a greater importance of issues like strain, even in the absence of dislocation defects, may still have an impact on heterostructured device design and performance, and indicate that the VEELS technique could ultimately provide unprecedented detail with respect to important electronic structure details.