Optical studies of growth and etch features on some crystal faces

Abstract

The work consists of optical and interferometric studies of growth, slip, and etch phenomena on diamond octahedral faces. For this study special experimental techniques have been developed. These comprise: (a) Thin film technique tor high magnification topographical studies. (b) Micro-flat for the study of rough surfaces. The study includes (1) Evaluation of inter-facial angles of growth hillocks and trigone, so familiar on diamond surfaces. This is carried out by means of multiple beam interferometry, the method competing with goniometry. A similar procedure is adopted to the etch pit. (2) Cylindrical curvature is discussed and values are obtained for both hillocks and vicinal faces. Trigons are similarly treated, but they are included in another study of a statistical nature (depth versus size). (3) A theory is developed to account for the existence of trigone. This is first presented as a speculation but is later supported by facts. (4) Slip has been substantiated to exist in diamond. This has been discovered and studied by means developed in this thesis. The slip plane has been identified as the (111) plane. An opacity has been observed (intimately connected with the slip) which has bean duly interpreted. (5) By artificially etching diamond at a much lower temperature than is usually adopted, etch pits have been observed to be spirally connected. The spirals are oriented in conformity with the crystal symmetry. The susceptibility of the shape and size of the etch pit to the etching temperature has been investigated, also the distribution of depth amongst the etch pits. (6) The temperature at which the diamond has formed is calculated, and a procedure to be adopted for the complete confirmation is outlined.