By using a nano-scale patterning process, a dislocation defect density of a GaN epitaxy layer can be further reduced. This is because the nano-scale epitaxy structure dimension is advantageous to the reduction of the strain energy accumulated by mismatched lattices, thereby decreasing the possibility of generating defects. It is verified that the nano-scale patterning process can effectively decrease the dislocation defect density of the GaN epitaxial layer on a sapphire substrate. Considering uniformity and reproducibility on the application of the large-size wafer, the invention has utilized the soft mask NIL patterning technology to successfully implement the uniform deposition and position control of the InAs quantum dot on a GaAs substrate. This further utilizes the NIL technology in conjunction with dry-etching to perform the nano-scale patterning on a heterogeneous substrate, such as Si, sapphire or the like. |