Semiconductors crystal defects

It was discovered by Al shits et al. (1987) that static magnetic fields of order 0.5T affect the motion of dislocations in NaCl crystals. This is not an intrinsic effect but is associated with impurities and/or radiation induced localized defects. Also, magnetic field effects have been observed in semiconductor crystals such as Si (Ossipyan et al., 2004). 

At all temperatures above 0°K Schottky, Frenkel, and antisite point defects are present in thermodynamic equilibrium, and it will not be possible to remove them by annealing or other thermal treatments. Unfortunately, it is not possible to predict, from knowledge of crystal structure alone, which defect type will be present in any crystal. However, it is possible to say that rather close-packed compounds, such as those with the NaCl structure, tend to contain Schottky defects. The important exceptions are the silver halides. More open structures, on the other hand, will be more receptive to the presence of Frenkel defects. Semiconductor crystals are more amenable to antisite defects. 

Inorganic semiconductors are crystalline in structure. They require high-quality materials, since they are very sensitive to impurities and crystal defects. Material design options for inorganic semiconductors include doping, alloying, and heterostructures. 

Defects or impurities in the semiconductor crystal structure create electronic states in the gap region. In the case of impurities, the valence character of the impurity determines whether the level acts as an electron donor or electron acceptor state. In doping semiconductors, impurities are deliberately used to generate either donor or... 

Chapter 1 of the present volume provides the basic concepts related to the properties and characterization of the centres known as shallow dopants, the paradigm of the H-like centres. This is followed by a short history of semiconductors, which is intimately connected with these centres, and by a section outlining their electrical and spectroscopic activities. Because of the diversity in the notations, I have included in this chapter a short section on the different notations used to denote the centres and their optical transitions. An overview of the origin of the presence of H-related centres in crystals and guidelines on their structural properties is given in Chap. 2. To define the conditions under which the spectroscopic properties of impurities can be studied, Chap. 3 presents a summary of the bulk optical properties of semiconductors crystals. Chapter 4 describes the spectroscopic techniques and methods used to study the optical absorption of impurity and defect centres and the methods used to produce controlled perturbations of this absorption, which provide information on the structure of the impurity centres, and eventually on some properties of the host crystal. Chapter 5 is a presentation of the effective-mass theory of impurity centres, which is the basis for a quantitative interpretation... 

It is always the objective in either an ionizatin or a semiconductor detector to collect all the charges produced by the incident particle. This is achieved by establishing an electric field in the detector such that there is zero recombination of electrons and ions (or holes) before they are collected. In a semiconductor detector, even if recombination is zero, some charge carriers may be lost in trapping centers of the crystal, such as lattice imperfections, vacancies and dislocations. The incident radiation creates crystal defects that cause deterioration of the detector performance and, thus, reduce its lifetime (see Sec. 7.6). 

---