Nanomaterials @ Interfaces Research Group

Lateral confined epitaxy (LCE) is an epitaxial growth method on substrates patterned to form uniform mesas separated by trenches for laterally restricting growth area. In this work, plan view and cross-sectional transmission electron microscopy (TEM) were used in order to characterize the microstructure of GaN films grown by metal-organic chemical vapor deposition on patterned Si (111) using the LCE method. Two kinds of propagation modes of the dislocations were observed. The dislocations in the center of the mesa mainly propagate vertically to the surface. On the other hand, dislocations close (1-2 μm) to the mesa edges tend to bend laterally, allowing dislocation reactions that result in a lower dislocation density. This suggests that the overall material quality improves with decreasing mesa size, which is consistent with the observed increase in photoluminescence band edge peak intensity.