The Study Of InGaN/GaN QW Structures Growth And The Growth Procedure Of SiN_x Thin Films

For their advantages of wide gap from0.7eV to6.2eV, and superior of extensive direct-band for optoelectronic application, III-nitride (GaN-based) semiconductors are the most useful material system for near-infrared-visible-ultraviolet(NIR-VIS-UV) optoelectronic device applications.In recent years, with the wide study and application of GaN-based LED, the manufacture of green and blue LED became quite mature. And GaN-based semiconductors gradually go into industry. Studies on InGaN material and InGaN/GaN quantum well structure are going perfect. However, what affect the performance of device are the growth of the semiconductor and its quality. Thus, it has significant meaning in research of manufacture of III-nitride semiconductors and its optoelectronic performance on optoelectronic devices. HRXRD, SEM, AFM, CL are some of the useful ways to do that research.In this article, we focus on the two issues. We use those technical to investigate the growth process of those films and their structure applications. And do research to improve the technology of SiNx films by PECVD. The main conclusions are listed as follows:1. High-quality InGaN/GaN heterojunction structures were grown by MOCVD on c-plane sapphire at different growth temperature with GaN buffer layers. The In content can be calculated from the peak of XRDω/20scan and the Vegared’s law, the crystal quality can be evaluated from the FWHM of Rocking Curve. The calculation results tell us In content in InGaN film will be influenced with different growth temperature. We got the In content of Samples in this article ranging from0.13to0.23. Meanwhile, the changing of FWHM reveal the difference of crystal quality. And another peak detected from XRD ω/2θ scan in some samples show possibility of In uneven distribution. Combination of EDS and SEM images prove that uneven distribution.2. We observed the change of growth mechanic in samples with various growth temperatures by SEM surface scan and AFM surface morphology. We concluded that films form3dimensional island model to2dimensional step-flow model when growth temperature raised. And samples were separated into two groups according to SEM scan images:pseudomorphic (0.13≤x≤0.16) and relaxed (0.18≤x≤0.23). Those two groups are systematically studied mainly based on Raman scattering technique. We also got the thickness of each layers in InGaN/GaN heteroj unction samples. Using MREI model we found pseudomorphic samples are fully strained and Residual strains in partially relaxed samples are also evaluated. Structure information was gathered by PANalytical X’PertEPITAXY4simulation.3. By studying SEM surface morphology and CL Mapping images we discussed the relationship between InGaN/GaN QW structure, morphology and radiation. Three defects with different characteristics were defined and systematically analyzed about the effect on luminescence.4. SiNx samples were manufactured by PECVD. Different deposition parameters were explored to find the effects on deposition speed. Growth technique was discussed and best deposition parameters were found.