Application Of High-resolution X-ray Diffraction Tachniques In GaN LED Production

Following the first generation Ge, Si semiconductor materials and the secondgeneration of GaAs, InP compound semiconductor materials, GaN based materials arecalled the third generation semiconductor materials. Their band gap are wide, and theyhave the characteristics of high electron saturation drift velocity, low dielectric constant,good thermal conductivity, good chemical and thermal stability, are quite suitable forthe fabrication of high temperature, high frequency and high power electronic devices.With the continuous improvement of technology, GaN based blue and green LED has toscale produced. However, the technology is not fully mature, there are still manyproblems to be solved, the pursuit of high power and high photoelectric conversionefficiency are still keys in the growth of LED.In practical applications, the epitaxial structure optimization is an important meansto enhance the efficiency of the device, and is an important basis for the test of crystalquality, structural parameters and analysis of structural and process optimization to thewafer. High-resolution X-ray diffraction techniques to quickly and accurately informedthe crystal quality of GaN epitaxial layer structure without damage, and is the ideal wayto achieve the above functions in the first time for the large-scale production of therequired data.a) This paper introduces three kinds of X ray diffraction technique, describes thephysical process of diffraction, and explains the parameter scanning method used and itstest by the Bede QC3high resolution X ray diffractometer.b) Through360°Phi scan of GaN epitaxial layer structure, we have analyzed thedistribution of diffraction space.c) By the rocking curve skew symmetric diffraction technique in thecharacterization, we get the method to describe the dislocation density in the epitaxiallayer.d) Using MQW thickness fitting method of GaN LED, characterize the effects onthe luminance and wavelength of LED.e) By the method of rotating a preliminary elimination equipment error, we havecalculated the lattice constant, and calculated the lattice constants accurately via themethod of multistage diffraction.f) By the method of rotating a preliminary elimination equipment error, we have calculated the lattice constant. On the base of calculating the lattice constants accurately,we have researched the compressive stress of the epitaxial layer, and learned a methodof multistage diffraction.