Influence of surface misorientation of HPHT diamond substrates on crystal morphologies and threading dislocations propagation



The production of diamond-based electronic devices for optical and electronic applications requires the control of point and extended defects that influence the exceptional properties of the material. While point defects in single crystal (Chemical Vapor Deposition) diamond have been studied for many years, relatively little has been reported on the extended defects content of this material. In particular, threading dislocations propagating parallel to the growth direction, act as killer defects within the CVD diamond film. In this work, different substrate surface misorientations have been investigated to evaluate their effect on dislocation propagation. Misorientation angles of 3.5°, 10°, and 20° along <100> and <110> directions as well as bevels of 10° along <100> and <110> directions were used. By using misorientations of 10° or above along the <110> directions it is possible to plasma etch the substrate surface prior to growth while keeping a smooth morphology. This affects defect density in the CVD film after growth and helps decreasing threading dislocations. In parallel, a growth model allowed us to predict the evolution of the top misoriented face and the crystal shape. This study aims at getting a better understanding of dislocations formation and propagation in order to prepare defect-free CVD diamond films.