The method of obtaining pure polycrystalline silicon is described, followed by short accounts of how this material is converted into single-crystal form either by the Czochralski (CZ) pulling method or the float-zone (FZ) method. It is shown that the silicon contains various impurities including oxygen, carbon, boron and possibly hydrogen. The defects and impurities often show a nonhomogeneous distribution in the form of helical swirls. Heat treatment of silicon-containing oxygen leads to the clustering of this impurity. At 450 degrees C there is formation of small complexes that act as shallow donors. Investigations using IR and ESR spectroscopy have so far failed to determine the atomic configuration of the defects. Heating at higher temperatures causes wide-scale precipitation of oxygen. There are interactions with carbon and there can be formation of silicon carbide precipitates. Contamination from Cu, Au, Fe, etc., can occur during these treatments and methods for gettering these metals are discussed, involving dislocations and silica precipitates. Low-temperature irradiations produce vacancies and self-interstitials which combine with impurities to form complexes on heating from 4K to 300K. Evidence is presented to illustrate the possible charge states of self-interstitials. Damage produced by fast neutrons is discussed next, followed by a brief account of neutron transmutation doping whereby neutrally occurring 30Si is converted to 31P by the capture of thermal neutrons. Some aspects of high-temperature diffusion are discussed and attempts are made to correlate the data with that derived from the irradiation studies.

https://iopscience.iop.org/article/10.1088/0034-4885/45/10/003/pdf

Defects in silicon

Non-radiative transitions affect many aspects of semiconductor performance. Normally they reduce device efficiency by suppressing luminescence, creating defects, reducing carrier lifetimes, or enhancing diffusion during operation. The present review surveys both the theoretical and practical understanding of non-radiative transitions. It includes general theoretical results and the associated ideas, with the emphasis on phonon-induced and defect Auger processes. Most of the purely formal aspects are omitted, but the points of principle where uncertainties remain are discussed. The review also covers the relation between basic theoretical studies and practical applied work on device degradation. This includes a description of the atomic processes involved in the more important mechanism of device deterioration and the theoretical understanding of the mechanism of these underlying processes. Finally, there is a survey of models proposed for 'killer' centres.

/pdf/non-radiative-transitions-in-semiconductors-2c1mre1fqm.pdf

Non-radiative transitions in semiconductors

Intrinsic defects in silicon

Publisher Summary The chapter presents a discussion on electronic structure of three-dimensional (3d) transition-atom impurities in semiconductors. The effects of 3d impurities in semiconductors have preoccupied the field since the invention of the transistor. Reliable experimental data for germanium and silicon became available quite early. The chapter presents an in-depth review of the present status of the field. This review contains a most careful and detailed exposition of various aspects of the subject, presented, as the author states using “the combined points of view of theoretical solid-state physics, semiconductor physics, and classical inorganic chemistry.” The chapter discusses the great progress that has been made. The chapter presents a review on the recent developments vis a vis the new experimental methodologies and the classical phenomenological approaches used earlier to understand deep 3d impurities. The author attempts to present a coherent picture of the understanding of isolated 3d impurities in cubic semiconductors from the combined points of view of theoretical solid-state physics, semiconductor physics, and classical inorganic chemistry.

Electronic Structure of 3d Transition-Atom Impurities in Semiconductors

Ion-induced defects in semiconductors

Interstitial boron in silicon: A negative- U system

We report the first observation of recombination-enhanced recovery of a defect in silicon which is otherwise normally stable at room temperature. This defect, produced by 1.5-MeV electron irradiation of aluminum-doped material at room temperature, is identified as isolated interstitial aluminum through correlated deep-level transient-capacitance spectroscopy and EPR studies. The recovery rate constant in the absence of minority-carrier injection is 3(${10}^{9}$) exp(- 1.2\ifmmode\pm\else\textpm\fi{}0.1 eV/kT) ${\mathrm{sec}}^{\ensuremath{-}1}$. Under saturated injection conditions, it is 70 exp(- 0.27\ifmmode\pm\else\textpm\fi{}0.03 eV/kT) ${\mathrm{sec}}^{\ensuremath{-}1}$. This represents an enhancement of the recovery rate by a factor of \ensuremath{\sim} ${10}^{8}$ at room temperature. We conclude that this enhancement results from an efficient conversion of the electronic energy available upon carrier capture to local vibrational energy of the defect which assists it over the migration barrier. The second donor level of the defect ($\frac{{\mathrm{Al}}_{i}^{+}}{{\mathrm{Al}}_{i}^{++}}$) is determined to be at ${E}_{V}+0.17$ eV. We conclude, however, that the enhancement results from carrier capture and recombination at the first donor level ($\frac{{\mathrm{Al}}_{i}^{0}}{{\mathrm{Al}}_{i}^{+}}$) the position of which has not yet been determined. The implications of these results to the properties of the self-interstitial in silicon are discussed.

J. R. Troxell

Papers

Interstitial boron in silicon: A negative- U system

Recombination-enhanced migration of interstitial aluminum in silicon