The motion of energetic charged particles inside a monocrystalline solid can be strongly influenced by channeling and blocking effects. The present article reviews the theory, the experimental studies, and some of the applications of these effects. The coverage of the published literature extends through June 1973.

Channeling and related effects in the motion of charged particles through crystals

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

The phenomenology is reviewed for several enhanced diffusion mechanisms: the normal ionization-enhanced diffusion mechanism, the Bourgoin mechanism, the energy-release mechanism and some recoil mechanisms. Application of these mechanisms are discussed for crystalline and amorphous semiconductors, super-ionic materials and insulators in radiation damage, impurity and self-diffusion, ion-implantation, and dislocation-motion-experiments.

Enhanced diffusion mechanisms

The influence of annealing on the concentration profiles of boron implanted into silicon with does of 1014 ions/cm2 up to 1016 ions/cm2 and an energy of 70 keV was studied. The concentration profiles were measured with Secondary Ion Mass Spectrometry (SIMS). The broadening of the concentration profiles during annealing can be described as a superposition of effects resulting from a relatively immobile and a mobile boron fraction. The properties of the immobile boron fraction were studied by measuring the influence of a boron implantation on the distribution of a homogeneous boron background dope. From these experiments it was concluded that the immobile boron fraction consists of boron precipitates. The properties of the mobile fraction were studied from concentration profiles that were obtained after annealing during different periods at the same temperature. It was found that during the initial stage of the annealing process a fast broadening of the profile occurs; this was assumed to be due to an interstitial type boron diffusion. After prolonged annealing the much slower substitutional type diffusion prevails, due to trapping of the interstitial boron atoms by vacancies. The reliability of the SIMS method, as applied to profile measurements, was checked for the high boron doses used in this investigation. Excessive boron precipitates, obtained after annealing of a high dose, such as 1016 ions/cm2 at about 1000°C, appear to give some increase of the ion yield.

Influence of Annealing on the Concentration Profiles of Boron Implantations in Silicon

A rapid numerical method of the calculation of X-ray rocking curves (RC) from crystals with thin surface damaged layers is developed on the basis of a semi-kinematical approach. The determination of the strain profile in the layer from experimental RC's by a „best correspondence” fitting procedure is demonstrated. Strain profiles in Si crystals doped with boron ions with energy from 40 to 100 keV are obtained and discussed in comparison with the distributions of impurity atoms and radiation defects found by other experimental techniques.



Eine schnelle numerische Berechnungsmethode fur Rontgen-Rocking-Kurven (RC) von Kristallen mit dunner Oberflachendamageschicht wird auf der Grundlage einer semikinematischen Methode entwickelt. Die Bestimmung des Spannungsprofils in der Schicht aus experimentellen RC-Kurven durch ein Fittungsverfahren der „besten Ubereinstimmung” wird demonstriert. Spannungsprofile in Si-Kristallen, die mit Bor-Ionen einer Energie von 40 bis 100 keV dotiert wurden, werden erhalten und im Vergleich zu Verteilungen von Storstellenatomen und Strahlungsdefekten diskutiert, die mit anderen experimentellen Technikengefunden werden.

Strain profiles in ion‐doped silicon obtained from X‐ray rocking curves

The channeling technique has been used to determine the lattice location of boron implanted into silicon by using the B11 (p,α) nuclear reaction. Approximately 30% of the boron lies on substitutional sites after a room‐temperature implantation of 3×1015/cm2. The substitutional content decreases with annealing temperature up to 700 °C and then increases at higher annealing temperature. This explains a reverse annealing behavior observed in the carrier concentration. Nearly all of the boron lies on substitutional sites after annealing at 1100 °C. The nonsubstitutional boron atoms do not occupy the normal tetrahedral interstitial sites. For annealing temperatures up to 500 °C they appear to lie along atomic rows, but they do not lie midway between row lattice sites. After higher‐temperature annealing their location appears less well‐defined.

J. C. North

Papers

Channeling study of boron‐implanted silicon