Backscattered electrons from semiconductors and their effect on the resolution of TSEM

The electron backscattering properties of clean Ge(100), GaAs(100), GaAs(111)B, Ga70Al30As(111)B, GaP(111)A, and Si(100) surfaces are studied in the 0.08–3-keV range at pressures below 50 pTorr. The kinetic energy distribution and the backscattered yield η(Er, Ep) are measured by ac and dc retarding field methods. The data on backscattering is used to estimate the influence of high-energy backscattered electrons on the resolution of Si and GaAs transmission secondary electron multipliers. The results show that the degradation in the modulation transfer function at low spatial frequencies is approximately 8% for GaAs and less than 4% for Si.