The study of sub-surface and interface characteristics of semiconductor heterostructures by slow positron implantation spectroscopy

Experiments are described in which the controlled implantation of mono-energetic positrons is used to gain information non-destructively on epilayer and interface defects in semiconductor heterostructures. The implantation, and hence annihilation, profile is changed by varying the incident positron energy from 1 to 35 keV. Characteristics of the positron state at the annihilation site are reflected in the width of the measured Doppler-broadened annihilation line. The fractions of positrons annihilating from each state are deduced by solving the steady-state diffusion equation. The technique is illustrated by application to a series of SiO 2 -Si samples.