Birefringence Microscopy of Unit Dislocations in Diamond

We use the rotating polarizer birefringence technique to investigate the properties of dislocations in single crystalline diamond produced by a high pressure high temperature (HPHT) process or by microwave plasma assisted chemical vapor deposition (MPACVD). The birefringence pattern of individual dislocations is measured and modeled. Although the combination of experiment and simulation does not permit identification of the Burgers vector with absolute certainty, the sensitivity is sufficient to show that the detected defects are unit dislocations. In most cases, the patterns are compatible with straight, threading edge, or mixed dislocations with Burgers vectors a/2[110] or a/2[011]. Birefringence microscopy can also be used to probe newly formed defects during the growth of a homoepitaxial layer.