Defect Characterization in Semiconductors with Positron Annihilation Spectroscopy

Abstract

Positron annihilation spectroscopy is an experimental technique that allows the selective detection of vacancy defects in semiconductors, providing a means to both identify and quantify them. This chapter gives an introduction to the principles of the positron annihilation techniques and then discusses the physics of some interesting observations on vacancy defects related to growth and doping of semiconductors. Illustrative examples are selected from studies performed in silicon, III-nitrides, and ZnO. A short overview of positron annihilation spectroscopy is given in Sect. 46.1. The identification of vacancies and their charge states is described in Sect. 46.2; this section also discusses how ion-type acceptors can be detected due to the positronsʼ shallow Rydberg states around negative ions. The role of vacancies in the electrical deactivation of dopants is discussed in Sect. 46.3, and investigations of the effects of growth conditions on the formation of vacancy defects are reviewed in Sect. 46.4. Section 46.5 gives a brief summary