Defects and Impurities at the Si/Si(100) Interface Studied with Monoenergetic Positrons

Positrons implanted with varying energies (0-20 keV) have been used to study silicon epilayers grown by molecular-beam epitaxy on Si(100) substrates. Defects at the initial growth interface and throughout the overlayer have been observed and depth profiled. In addition, field-driven positron drift observed in some of the epilayers is shown to be consistent with estimated concentrations of (active) interfacial impurities. The study demonstrates that positrons can be used nondestructively to profile structural defects and electric fileds in thin films and at interfaces.