G. R. Booker

Surface damage on abraded silicon specimens

Abstract Single crystal Si specimens have been unidirectionally abraded, the abrasives ranging from 0•25 micron diamond to No. 240 SiC paper, and examined by transmission electron microscopy and standard metallographic methods. The investigation showed that the damage varied in a progressive manner with the severity of the abrasion treatment, ranging from rows of single dislocations to bands of both dislocation networks and cracked material. The corresponding depths of damage ranged from approximately 0•2 to 24 microns. Anisotropy of damage occurred for the fine abrasions (often termed polishing), but was not observed for the coarse abrasions. When abraded specimens were annealed, the dislocations changed their configuration, and new dislocations propagated in order to relieve elastic strains. A qualitative description of the abrasion process for Si based on the results of the investigation is given.

Growth of epitaxial silicon layers by vacuum evaporation

Abstract Epitaxial Si layers have been grown on single crystal Si substrates by the vacuum evaporation method. The apparatus and experimental procedure used are described, and an initial assessment of the layers is given. The growth was markedly dependent on the deposition rate. In particular, when the rate was increased beyond a certain critical value, no stacking-fault defects occurred in the layers.

Two-dimensional defects in silicon after annealing in wet oxygen

Abstract After a silicon slice with a mechanically damaged surface was annealed at 1200°C for 2 hours in wet oxygen, two-dimensional defects were present extending from the surface into the slice. The defects are shown to be thin plates of amorphous material, probably oxide, and it is suggested that they arise by a mechanism analogous to that described by Silcock and Tunstall (1964) for the precipitation of NbC in steel.

Observations on dislocation nodes in silicon

Abstract Dislocation nodes which are not extended may appear to be extended in transmission electron micrographs because of a diffraction contrast effect. Any values of stacking-fault energy deduced from such nodes using the conventional formulae are likely to be incorrect. Nodes in silicon seem to be of this type.

A study of nucleation in chemically grown epitaxial silicon films using molecular beam techniques: V. Nucleation kinetic measurements on (100) surfaces

Abstract The study of nucleation kinetics in the autoepitaxial growth of silicon from a molecular beam of silane on (111) oriented substrates reported in Paper III (Joyce, Bradley and Booker 1967) has been extended to (100) substrates. Measurements of the dependence of the saturation number density of growth centres on time, substrate temperature and beam intensity have been made, and the spatial distribution of growth centres determined and compared with a completely random distribution. Analysis of these results in terms of the theory developed in Paper III shows good qualitative agreement, and physically reasonable values for the number of atoms in the smallest stable nucleus and the activation energy of surface diffusion have been deduced. However, complete quantitative agreement has not yet been obtained between theoretical and experimental results.

Tripyramids and associated defects in epitaxial silicon layers

Abstract Tripyramids and the associated defects present in epitaxial Si layers grown on (111) Si substrates have been examined by transmission electron microscopy and selected-area transmission electron diffraction, and their nature and crystallography directly determined. The tripyramids consist of a central triangular area, twinned about the (111) substrate plane, together with three surrounding segments, each initially twinned about the (111) substrate plane and subsequently twinned about an inclined {111} plane. The associated defects mostly consist of micro-twin lamellae, each twinned about an inclined {111} plane. The different types of interface occurring in the tripyramids are discussed, and mechanisms are suggested to account for the formation of both the tripyramids and the associated defects.

Investigation of epitaxial silicon layers grown in the presence of small quantities of gold

Abstract Three epitaxial silicon layers, grown under varying conditions in the presence of small quantities of gold, are examined, both before and after etching, by transmission and scanning electron microscopy. The results show that the presence of an extremely thin silicon/gold alloy layer (< 100 A) on the growing surface can extensively alter the growth characteristics. Two possible growth mechanisms involving such an ultra-thin alloy layer are outlined.

Observations of silicon at high temperature by transmission electron microscopy

Transmission electron microscope observations have been made on epitaxial Si layers using a heating goniometer holder (Valdre 1965). Preliminary results are reported on the annealing of stacking fa...

Perfection of Expitaxial Silicon Layers Grown by the Pyrolysis of Silane

Abstract Epitaxial silicon layers have been grown by the pyrolysis of silane on silicon substrates cut parallel to the {110}. The stacking-fault density and the overall crystalline perfection of the layers have been determined as a function of layer growth rate. The density of stacking faults decreased with increasing rate, but the overall perfection, as indicated by the sharpness of Kikuchi lines in transmission electron diffraction, was found to deteriorate with increasing rate. The characteristics of point contact diodes made at a number of places on individual layers have been determined and compared with the degree of crystal perfection.