Since the 1997 publication of Silicon Carbide - A Review of Fundamental Questions and Applications to Current Device Technology edited by Choyke, et al., there has been impressive progress in both the fundamental and developmental aspects of the SiC field. So there is a growing need to update the scientific community on the important events in research and development since then. The editors have again gathered an outstanding team of the world's leading SiC researchers and design engineers to write on the most recent developments in SiC. The book is divided into five main categories: theory, crystal growth, characterization, processing and devices. Every attempt has been made to make the articles as up-to-date as possible and assure the highest standards of accuracy. As was the case for earlier SiC books, many of the articles will be relevant a decade from now so that this book will take its place next to the earlier work as a permanent and essential reference volume.

We report on a new type of quantum wells with the width as thin as 10Å, which are composed of SiC only, and consequently have ideal interfaces. These quantum wells are actually stacking faults in SiC. Certain types of stacking faults in SiC polytypes create small 3C-like regions, where the stacking sequences along the c-axis become locally cubic in the hexagonal host crystals. Since the conduction band offsets between the cubic and hexagonal polytypes are very large with the conduction band minima of 3C-SiC lower than that of the other polytypes, such thin 3C inclusions can introduce locally lower conduction bands, thus acting as quantum films perpendicular to the c-axis. One mechanism for the occurrence of stacking faults in the perfect SiC single crystals is the motion of partial dislocations in the basal planes, the partial dislocations leaving behind stacking fault regions. © 2003 Elsevier Science Ltd. All rights reserved.

A ab initio study of 3 C inclusions and stacking fault-stacking fault interactions in 6H-SiC was presented. The electronic structures and the total energies of 6H-SiC single crystals that contain one, two, three and four stacking faults were studied. The possibility of local hexagonal to cubic polytypic transformations was discussed in light of the formation energy and quantum-well action.

The multiple stacking faults in 4H-SiC, leading to narrow 3C polytype inclusions along the hexagonal c direction, were discussed. The stacking fault energies for successive stacking faults were calculated. The analysis showed that the stacking fault energy for the two stacking faults in adjacent basal planes was reduced by approximately a factor of 4 relative to that of one isolated stacking fault.

Stress in epitaxial layers due to crystal lattice mismatch directly influences the growth, structure, and basic electrophysical parameters of epitaxial films and also to a large extent the degradation processes in semiconductor devices. In this letter, we present a theoretical model for calculating the induced lattice compression due to N doping and the critical thickness concerning formation of misfit dislocations in homoepitaxial 4H–SiC layers with different N-doping levels. For example: The model predicts that substrates with a N concentration of 3×10¹⁹ cm^-3 induce misfit dislocations when the epilayer thickness reaches ∼10 μm. Also, the N-doping concentration in the 1×10¹⁸–1×10¹⁹ cm^-3 range yields a strain that not will cause misfit dislocactions at the substrate and epilayer interface until an epilayer thickness of 200–300 μm is reached. Supporting evidence of the induced lattice compression due to N doping have been done by synchrotron white-beam x-ray topography on samples with different N-doping levels and are compared with the predicted results from the model

Stress in epitaxial layers due to crystal lattice mismatch directly influences growth, structure, and basic electro-physical parameters of epitaxial films and also to a large extent the degradation processes in semiconductor devices. In this paper we present a theoretical model for calculating the induced lattice compression due to N doping and the critical thickness concerning formation of misfit dislocations in homoepitaxial 4H-SiC layers with different N doping levels. For example: The model predicts that substrates with N concentration of 3E19 induce misfit dislocations when the epilayer thickness reaches similar to10 mum. Also, N doping concentration in the 1E18-1E19 range yields a strain that not will cause misfit dislocactions at the substrate and epilayer interface until an epilayer thickness of 200-300 mum is reached. Supporting evidence of the induced lattice compression due to N doping have been done by synchrotron white-beam x-ray topography on samples with different N doping level and are compared with the predicted results from the model.

The main purpose of this article is to determine the two-dimensional effective mass tensors of electrons confined in thin 3C wells in hexagonal SiC, which is a first step in the understanding of in-plane electron motion in the novel quantum structures. We have performed ab initio band structure calculations, based on the density functional theory in the local density approximation, for single and multiple stacking faults leading to thin 3C-like regions in 4H- and 6H-SiC and deduced electron effective masses for two-dimensional electron gases around the cubic inclusions. We have found that electrons confined in the thin 3C-like layers have clearly heavier effective masses than in the perfect bulk 3C-SiC single crystal.

First-principles calculations of twin boundaries in 3C-SiC, Si, and diamond are performed, based on the density-functional theory in the local density approximation. We have investigated the formation energies and electronic properties of isolated and interacting twin boundaries. It is found that in 3C-SiC, interacting twin boundaries which are separated by more than two Si-C bilayers are actually energetically more favorable, implying a relatively frequent appearance of these defects. The effect of the spontaneous polarization associated with the hexagonal symmetry around twin boundaries is also studied, and we have observed that the wave functions belonging to the conduction- and valence-band edge states in 3C-SiC tend to be localized almost exclusively on different sides of the faulted layers, while there is no such feature in Si or diamond.

Recent attempts to make SiC diodes have revealed a problem with stacking fault expansion in the material, leading to unstable devices. In this paper, we present detailed results from a density-functional supercell calculation on the electronic structure of stacking faults which result from glide of Shockley partials in 3C-, 4H- and 6H-SiC. It was found [Phys. Rev. B 65, 033203 (2002)] that both types of stacking faults in 4H-SiC and two types of stacking faults in 6H-SiC give rise to band states, which are strongly localized (confined within around 10 Angstrom) in the direction orthogonal to the stacking fault plane. Based on estimates of the band offsets between different polytypes and a simple quantum-well theory, we show that it is possible to interpret this one-dimensional localization as a quantum-well confinement effect. We also find that the third type of stacking fault in 6H-SiC and the only stacking fault in 3C-SiC do not give rise to states clearly separated from the band edges, but instead give rise to rather strongly localized band states with energies very close to the band edges. We argue that these localized near band edge states are created by stacking fault induced changes in the dipole moment associated with the hexagonal symmetry. In addition, we have also calculated the stacking fault energies, using both the supercell method and the simpler ANNNI (axial next nearest-neighbor Ising) model. Both theories agree well with the low stacking fault energies found experimentally.

We review of our theoretical work on various stacking faults in SiC polytypes. Since the discovery of the electronic degradation phenomenon in 4H-SiC p-i-n diodes, stacking faults in SiC have become a subject of intensive study around the globe. At the beginning of our research project, the aim was to find the culprit for the degradation phenomenon, but in the course of this work we uncovered a wealth of information for the general properties of stacking faults in SiC. An intuitive perspective to the diverse nature of stacking faults in SiC will be given in this conference report. (C) 2003 Published by Elsevier B.V.