Quantitative analysis of semiconductor alloy composition during growth by reflection-electron energy loss spectroscopy

Determination of alloy composition during epitaxial growth of GexSi1–x alloys has been demonstrated using reflection-electron energy loss spectroscopy (REELS) at reflection high-energy electron diffraction (RHEED) energies. Measurements of inelastic scattering intensities from Si K (1840 eV) and Ge L2,3 (1217 eV) core losses were performed using a conventional RHEED gun together with an electron energy loss spectrometer in a molecular beam epitaxy system. Comparison of ex situ composition measurements by Rutherford backscattering and energy dispersive x-ray spectroscopy in a transmission electron microscope indicate excellent agreement with composition determination by REELS, demonstrating the capability of REELS as a quantitative in situ analysis technique. Application of REELS to other semiconductors is discussed and initial results for III–V and II–VI semiconductor alloys (GaAs, CdTe, and ZnTe) are also presented.