Gan Led Wafer Micro-structure Analysis And Performance Study

Gallium nitride (GaN) is wide band Semiconductor material with a hexagonal wurtzite crystal structure. At room temperature, its direct band gap is 3.39eV. It's representation of the third generation semiconductor, with the following advantages: high thermal conductivity, insoluble in acids and base,hardness etc. GaN material is extensively fabricated Laser diode,Light-emitting diode (including green,blue,UV) and high-temperature power devices for its unique property.In recent years, GaN-based optoelectronic materials and devices have been rapidly developed, but GaN thin films have not been fully studied. Many theoretical and experimental studies should be focused on the GaN-based materials and properties, especially these problems affected industrialization. So far, almost all of the published papers are regarded on the density of threading dislocations in GaN. In this thesis, high-resolution X-ray diffraction and transmission electron microscope were used to analyze the microstruction of GaN LED on sapphire substrate. The main content of this thesis and some main conclusions are as follows:1. The crystal structures were determined by the absolute measurement andΦscan. The results show that the GaN films have high symmetry of hexagonal. And the specular reflection scan was used to study the GaN film, it can observe a Prague peak and a Satellite interference peak, indicated that the sample was high quality layer by layer supperlattice structure. In-plane grazing incidence was used to determine the mosaic structures of the GaN films, and the dislocation density was obtained, most of the dislocation is edge dislocation, screw dislocation and mixed dislocation is relatively few. The growth direction of the grain size is also measured.2. The superlattice structure of the GaN films was measured by the HRXRD.3. The results of analysis by the transmission electron microscope show that: the epitaxial wafer has good layered structure; the thickness is uniform.4. The photoluminescence test showed that the sample had two Photoluminescence peak, and discussed the reason of the photoluminescence.5. The photolithography was used to make the light emitting diode (LED) the I-V curve showed that the device has good commutate quality.