Chapter 6 Perturbed Angular Correlation Studies of Defects

Abstract

This chapter focuses on the perturbed angular correlation studies of defects. Radioactive probe atoms in combination with the perturbed angular correlation technique (PAC) contribute to the identification of different types of defects in different semiconductors—elemental as well as III-Vs and II-VIs. Progress in semiconductor technology is driven by progress in the knowledge and control of defects; these include intrinsic defects, such as vacancies, self-interstitials, and extrinsic defects, such as dopants and impurity atoms in these materials. One of the key problems in the control of electrical properties of semiconductors concerns the influence of the doping procedure and thermal treatment of a sample on the degree of electrical activation of the dopants. The mechanisms that cause the compensation or passivation of the dopants should be understood. Analytical techniques include electrical transport measurements, capacitance-voltage (C-V) measurements, deep-level transient spectroscopy (DLTS), and photoluminescence spectroscopy (PL). In semiconductors that have lattices with lower than cubic symmetry, the lattice site of an isolated probe atom serves as a dopant can be inferred directly from the electric field gradient produced by the charge distribution of the host lattice.