Spatially-resolved and polarization-resolved photoluminescence for study of dislocations and strain in III–V materials

Unstrained III–V materials have a cubic structure and, owing to symmetry, the probabilities of light being emitted in any two orthogonal polarizations are equal. Mechanical strain, in general, reduces the symmetry of III–V materials and the probabilities of light being emitted in any two orthogonal polarizations are not necessarily equal. Thus the strain in luminescent III–V materials can be deduced from measurements of the degree of polarization of luminescence (DOP). Dislocations create characteristic strain fields. The type, direction, and Burgers vector of dislocations near the surfaces of luminescent III–V materials can be determined by matching measured patterns of DOP with predicted patterns that are based on the characteristic strain fields. In addition, strain fields for defects, quantum wells, interfaces, and steps of fabrication in III–V materials can be imaged and investigated by analysis of the DOP.